Search Results

Search found 21115 results on 845 pages for 'byte order'.

Page 192/845 | < Previous Page | 188 189 190 191 192 193 194 195 196 197 198 199  | Next Page >

  • How customers view and interact with a company

    The Harvard Business Review article written by Rayport and Jaworski is aptly titled “Best Face Forward” because it sheds light on how customers view and interact with a company. In the past most business interaction between customers was performed in a face to face meeting where one party would present an item for sale and then the other would decide whether to purchase the item. In addition, if there was a problem with a purchased item then they would bring the item back to the person who sold the item for resolution. One of my earliest examples of witnessing this was when I was around 6 or 7 years old and I was allowed to spend the summer in Tennessee with my Grandparents. My Grandfather had just written a book about the local history of his town and was selling them to his friends and local bookstores. I still remember he offered to pay me a small commission for every book I helped him sell because I was carrying the books around for him. Every sale he made was face to face with his customers which allowed him to share his excitement for the book with everyone. In today’s modern world there is less and less human interaction as the use of computers and other technologies allow us to communicate within seconds even though both parties may be across the globe or just next door. That being said, customers view a company through multiple access points called faces that represent the ability to interact without actually seeing a human face. As a software engineer this is a good and a bad thing because direct human interaction and technology based interaction have both good and bad attributes based on the customer. How organizations coordinate business and IT functions, to provide quality service varies based on each individual business and the goals and directives put in place by its management. According to Rayport and Jaworski, the type of interaction used through a particular access point may lend itself to be people-dominate, machine-dominate, or a combination of both. The method by which a company communicates information through an access point is a strategic choice that relates costs and customer outcomes. To simplify this, the choice is based on what can give the customer the best experience interacting with the company when the cost of the interaction is also a factor. I personally see examples of this every day at work. The company website is machine-dominate with people updating and maintaining information, our groups department is people dominate because most of the customer interaction is done at the customers location and is backed up by machine based data sources, and our sales/member service department is a hybrid because employees work in tandem with machines in order for them to assist customers with signing up or any other issue they may have. The positive and negative aspects of human and machine interfaces are a key aspect in deciding which interface to use when allowing customers to access a company or a combination of the two. Rayport and Jaworski also used MIT professor Erik Brynjolfsson preliminary catalog of human and machine strengths. He stated that humans outperform machines in judgment, pattern recognition, exception processing, insight, and creativity. I have found this to be true based on the example of how sales and member service reps at my company handle a multitude of questions and various situations with a lot of unknown variables. A machine interface could never effectively be able to handle these scenarios because there are too many variables to consider and would not have the built-in logic to process each customer’s claims and needs. In addition, he also stated that machines outperform humans in collecting, storing, transmitting and routine processing. An example of this would be my employer’s website. Customers can simply go online and purchase a product without even talking to a sales or member services representative. The information is then stored in a database so that the customer can always go back and review there order, and access their selected services. A human, no matter how smart they are would never be able to keep track of hundreds of thousands of customers let alone know what they purchased or how much they paid. In today’s technology driven economy every company must offer their customers multiple methods of accessibly in order to survive. The more of an opportunity a company has to create a positive experience for their customers, in my opinion, they more likely the customer will return to that company again. I have noticed this with my personal shopping habits and experiences. References Rayport, J., & Jaworski, B. (2004). Best Face Forward. Harvard Business Review, 82(12), 47-58. Retrieved from Business Source Complete database.

    Read the article

  • Developing Schema Compare for Oracle (Part 5): Query Snapshots

    - by Simon Cooper
    If you've emailed us about a bug you've encountered with the EAP or beta versions of Schema Compare for Oracle, we probably asked you to send us a query snapshot of your databases. Here, I explain what a query snapshot is, and how it helps us fix your bug. Problem 1: Debugging users' bug reports When we started the Schema Compare project, we knew we were going to get problems with users' databases - configurations we hadn't considered, features that weren't installed, unicode issues, wierd dependencies... With SQL Compare, users are generally happy to send us a database backup that we can restore using a single RESTORE DATABASE command on our test servers and immediately reproduce the problem. Oracle, on the other hand, would be a lot more tricky. As Oracle generally has a 1-to-1 mapping between instances and databases, any databases users sent would have to be restored to their own instance. Furthermore, the number of steps required to get a properly working database, and the size of most oracle databases, made it infeasible to ask every customer who came across a bug during our beta program to send us their databases. We also knew that there would be lots of issues with data security that would make it hard to get backups. So we needed an easier way to be able to debug customers issues and sort out what strange schema data Oracle was returning. Problem 2: Test execution time Another issue we knew we would have to solve was the execution time of the tests we would produce for the Schema Compare engine. Our initial prototype showed that querying the data dictionary for schema information was going to be slow (at least 15 seconds per database), and this is generally proportional to the size of the database. If you're running thousands of tests on the same databases, each one registering separate schemas, not only would the tests would take hours and hours to run, but the test servers would be hammered senseless. The solution To solve these, we needed to be able to populate the schema of a database without actually connecting to it. Well, the IDataReader interface is the primary way we read data from an Oracle server. The data dictionary queries we use return their data in terms of simple strings and numbers, which we then process and reconstruct into an object model, and the results of these queries are identical for identical schemas. So, we can record the raw results of the queries once, and then replay these results to construct the same object model as many times as required without needing to actually connect to the original database. This is what query snapshots do. They are binary files containing the raw unprocessed data we get back from the oracle server for all the queries we run on the data dictionary to get schema information. The core of the query snapshot generation takes the results of the IDataReader we get from running queries on Oracle, and passes the row data to a BinaryWriter that writes it straight to a file. The query snapshot can then be replayed to create the same object model; when the results of a specific query is needed by the population code, we can simply read the binary data stored in the file on disk and present it through an IDataReader wrapper. This is far faster than querying the server over the network, and allows us to run tests in a reasonable time. They also allow us to easily debug a customers problem; using a simple snapshot generation program, users can generate a query snapshot that could be sent along with a bug report that we can immediately replay on our machines to let us debug the issue, rather than having to obtain database backups and restore databases to test systems. There are also far fewer problems with data security; query snapshots only contain schema information, which is generally less sensitive than table data. Query snapshots implementation However, actually implementing such a feature did have a couple of 'gotchas' to it. My second blog post detailed the development of the dependencies algorithm we use to ensure we get all the dependencies in the database, and that algorithm uses data from both databases to find all the needed objects - what database you're comparing to affects what objects get populated from both databases. We get information on these additional objects using an appropriate WHERE clause on all the population queries. So, in order to accurately replay the results of querying the live database, the query snapshot needs to be a snapshot of a comparison of two databases, not just populating a single database. Furthermore, although the code population queries (eg querying all_tab_cols to get column information) can simply be passed straight from the IDataReader to the BinaryWriter, we need to hook into and run the live dependencies algorithm while we're creating the snapshot to ensure we get the same WHERE clauses, and the same query results, as if we were populating straight from a live system. We also need to store the results of the dependencies queries themselves, as the resulting dependency graph is stored within the OracleDatabase object that is produced, and is later used to help order actions in synchronization scripts. This is significantly helped by the dependencies algorithm being a deterministic algorithm - given the same input, it will always return the same output. Therefore, when we're replaying a query snapshot, and processing dependency information, we simply have to return the results of the queries in the order we got them from the live database, rather than trying to calculate the contents of all_dependencies on the fly. Query snapshots are a significant feature in Schema Compare that really helps us to debug problems with the tool, as well as making our testers happier. Although not really user-visible, they are very useful to the development team to help us fix bugs in the product much faster than we otherwise would be able to.

    Read the article

  • ROracle support for TimesTen In-Memory Database

    - by Sherry LaMonica
    Today's guest post comes from Jason Feldhaus, a Consulting Member of Technical Staff in the TimesTen Database organization at Oracle.  He shares with us a sample session using ROracle with the TimesTen In-Memory database.  Beginning in version 1.1-4, ROracle includes support for the Oracle Times Ten In-Memory Database, version 11.2.2. TimesTen is a relational database providing very fast and high throughput through its memory-centric architecture.  TimesTen is designed for low latency, high-volume data, and event and transaction management. A TimesTen database resides entirely in memory, so no disk I/O is required for transactions and query operations. TimesTen is used in applications requiring very fast and predictable response time, such as real-time financial services trading applications and large web applications. TimesTen can be used as the database of record or as a relational cache database to Oracle Database. ROracle provides an interface between R and the database, providing the rich functionality of the R statistical programming environment using the SQL query language. ROracle uses the OCI libraries to handle database connections, providing much better performance than standard ODBC.The latest ROracle enhancements include: Support for Oracle TimesTen In-Memory Database Support for Date-Time using R's POSIXct/POSIXlt data types RAW, BLOB and BFILE data type support Option to specify number of rows per fetch operation Option to prefetch LOB data Break support using Ctrl-C Statement caching support Times Ten 11.2.2 contains enhanced support for analytics workloads and complex queries: Analytic functions: AVG, SUM, COUNT, MAX, MIN, DENSE_RANK, RANK, ROW_NUMBER, FIRST_VALUE and LAST_VALUE Analytic clauses: OVER PARTITION BY and OVER ORDER BY Multidimensional grouping operators: Grouping clauses: GROUP BY CUBE, GROUP BY ROLLUP, GROUP BY GROUPING SETS Grouping functions: GROUP, GROUPING_ID, GROUP_ID WITH clause, which allows repeated references to a named subquery block Aggregate expressions over DISTINCT expressions General expressions that return a character string in the source or a pattern within the LIKE predicate Ability to order nulls first or last in a sort result (NULLS FIRST or NULLS LAST in the ORDER BY clause) Note: Some functionality is only available with Oracle Exalytics, refer to the TimesTen product licensing document for details. Connecting to TimesTen is easy with ROracle. Simply install and load the ROracle package and load the driver. > install.packages("ROracle") > library(ROracle) Loading required package: DBI > drv <- dbDriver("Oracle") Once the ROracle package is installed, create a database connection object and connect to a TimesTen direct driver DSN as the OS user. > conn <- dbConnect(drv, username ="", password="", dbname = "localhost/SampleDb_1122:timesten_direct") You have the option to report the server type - Oracle or TimesTen? > print (paste ("Server type =", dbGetInfo (conn)$serverType)) [1] "Server type = TimesTen IMDB" To create tables in the database using R data frame objects, use the function dbWriteTable. In the following example we write the built-in iris data frame to TimesTen. The iris data set is a small example data set containing 150 rows and 5 columns. We include it here not to highlight performance, but so users can easily run this example in their R session. > dbWriteTable (conn, "IRIS", iris, overwrite=TRUE, ora.number=FALSE) [1] TRUE Verify that the newly created IRIS table is available in the database. To list the available tables and table columns in the database, use dbListTables and dbListFields, respectively. > dbListTables (conn) [1] "IRIS" > dbListFields (conn, "IRIS") [1] "SEPAL.LENGTH" "SEPAL.WIDTH" "PETAL.LENGTH" "PETAL.WIDTH" "SPECIES" To retrieve a summary of the data from the database we need to save the results to a local object. The following call saves the results of the query as a local R object, iris.summary. The ROracle function dbGetQuery is used to execute an arbitrary SQL statement against the database. When connected to TimesTen, the SQL statement is processed completely within main memory for the fastest response time. > iris.summary <- dbGetQuery(conn, 'SELECT SPECIES, AVG ("SEPAL.LENGTH") AS AVG_SLENGTH, AVG ("SEPAL.WIDTH") AS AVG_SWIDTH, AVG ("PETAL.LENGTH") AS AVG_PLENGTH, AVG ("PETAL.WIDTH") AS AVG_PWIDTH FROM IRIS GROUP BY ROLLUP (SPECIES)') > iris.summary SPECIES AVG_SLENGTH AVG_SWIDTH AVG_PLENGTH AVG_PWIDTH 1 setosa 5.006000 3.428000 1.462 0.246000 2 versicolor 5.936000 2.770000 4.260 1.326000 3 virginica 6.588000 2.974000 5.552 2.026000 4 <NA> 5.843333 3.057333 3.758 1.199333 Finally, disconnect from the TimesTen Database. > dbCommit (conn) [1] TRUE > dbDisconnect (conn) [1] TRUE We encourage you download Oracle software for evaluation from the Oracle Technology Network. See these links for our software: Times Ten In-Memory Database,  ROracle.  As always, we welcome comments and questions on the TimesTen and  Oracle R technical forums.

    Read the article

  • Developing Schema Compare for Oracle (Part 6): 9i Query Performance

    - by Simon Cooper
    All throughout the EAP and beta versions of Schema Compare for Oracle, our main request was support for Oracle 9i. After releasing version 1.0 with support for 10g and 11g, our next step was then to get version 1.1 of SCfO out with support for 9i. However, there were some significant problems that we had to overcome first. This post will concentrate on query execution time. When we first tested SCfO on a 9i server, after accounting for various changes to the data dictionary, we found that database registration was taking a long time. And I mean a looooooong time. The same database that on 10g or 11g would take a couple of minutes to register would be taking upwards of 30 mins on 9i. Obviously, this is not ideal, so a poke around the query execution plans was required. As an example, let's take the table population query - the one that reads ALL_TABLES and joins it with a few other dictionary views to get us back our list of tables. On 10g, this query takes 5.6 seconds. On 9i, it takes 89.47 seconds. The difference in execution plan is even more dramatic - here's the (edited) execution plan on 10g: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 108K| 939 || 1 | SORT ORDER BY | | 108K| 939 || 2 | NESTED LOOPS OUTER | | 108K| 938 ||* 3 | HASH JOIN RIGHT OUTER | | 103K| 762 || 4 | VIEW | ALL_EXTERNAL_LOCATIONS | 2058 | 3 ||* 20 | HASH JOIN RIGHT OUTER | | 73472 | 759 || 21 | VIEW | ALL_EXTERNAL_TABLES | 2097 | 3 ||* 34 | HASH JOIN RIGHT OUTER | | 39920 | 755 || 35 | VIEW | ALL_MVIEWS | 51 | 7 || 58 | NESTED LOOPS OUTER | | 39104 | 748 || 59 | VIEW | ALL_TABLES | 6704 | 668 || 89 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2025 | 5 || 106 | VIEW | ALL_PART_TABLES | 277 | 11 |------------------------------------------------------------------------------- And the same query on 9i: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 16P| 55G|| 1 | SORT ORDER BY | | 16P| 55G|| 2 | NESTED LOOPS OUTER | | 16P| 862M|| 3 | NESTED LOOPS OUTER | | 5251G| 992K|| 4 | NESTED LOOPS OUTER | | 4243M| 2578 || 5 | NESTED LOOPS OUTER | | 2669K| 1440 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 ||* 50 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2043 | ||* 66 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_TABLES | 1777K| ||* 80 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_LOCATIONS | 1744K| ||* 96 | VIEW | ALL_PART_TABLES | 852K| |------------------------------------------------------------------------------- Have a look at the cost column. 10g's overall query cost is 939, and 9i is 55,000,000,000 (or more precisely, 55,496,472,769). It's also having to process far more data. What on earth could be causing this huge difference in query cost? After trawling through the '10g New Features' documentation, we found item 1.9.2.21. Before 10g, Oracle advised that you do not collect statistics on data dictionary objects. From 10g, it advised that you do collect statistics on the data dictionary; for our queries, Oracle therefore knows what sort of data is in the dictionary tables, and so can generate an efficient execution plan. On 9i, no statistics are present on the system tables, so Oracle has to use the Rule Based Optimizer, which turns most LEFT JOINs into nested loops. If we force 9i to use hash joins, like 10g, we get a much better plan: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 7587K| 3704 || 1 | SORT ORDER BY | | 7587K| 3704 ||* 2 | HASH JOIN OUTER | | 7587K| 822 ||* 3 | HASH JOIN OUTER | | 5262K| 616 ||* 4 | HASH JOIN OUTER | | 2980K| 465 ||* 5 | HASH JOIN OUTER | | 710K| 432 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 || 50 | VIEW | ALL_PART_TABLES | 852K| 104 || 78 | VIEW | ALL_TAB_COMMENTS | 2043 | 14 || 93 | VIEW | ALL_EXTERNAL_LOCATIONS | 1744K| 31 || 106 | VIEW | ALL_EXTERNAL_TABLES | 1777K| 28 |------------------------------------------------------------------------------- That's much more like it. This drops the execution time down to 24 seconds. Not as good as 10g, but still an improvement. There are still several problems with this, however. 10g introduced a new join method - a right outer hash join (used in the first execution plan). The 9i query optimizer doesn't have this option available, so forcing a hash join means it has to hash the ALL_TABLES table, and furthermore re-hash it for every hash join in the execution plan; this could be thousands and thousands of rows. And although forcing hash joins somewhat alleviates this problem on our test systems, there's no guarantee that this will improve the execution time on customers' systems; it may even increase the time it takes (say, if all their tables are partitioned, or they've got a lot of materialized views). Ideally, we would want a solution that provides a speedup whatever the input. To try and get some ideas, we asked some oracle performance specialists to see if they had any ideas or tips. Their recommendation was to add a hidden hook into the product that allowed users to specify their own query hints, or even rewrite the queries entirely. However, we would prefer not to take that approach; as well as a lot of new infrastructure & a rewrite of the population code, it would have meant that any users of 9i would have to spend some time optimizing it to get it working on their system before they could use the product. Another approach was needed. All our population queries have a very specific pattern - a base table provides most of the information we need (ALL_TABLES for tables, or ALL_TAB_COLS for columns) and we do a left join to extra subsidiary tables that fill in gaps (for instance, ALL_PART_TABLES for partition information). All the left joins use the same set of columns to join on (typically the object owner & name), so we could re-use the hash information for each join, rather than re-hashing the same columns for every join. To allow us to do this, along with various other performance improvements that could be done for the specific query pattern we were using, we read all the tables individually and do a hash join on the client. Fortunately, this 'pure' algorithmic problem is the kind that can be very well optimized for expected real-world situations; as well as storing row data we're not using in the hash key on disk, we use very specific memory-efficient data structures to store all the information we need. This allows us to achieve a database population time that is as fast as on 10g, and even (in some situations) slightly faster, and a memory overhead of roughly 150 bytes per row of data in the result set (for schemas with 10,000 tables in that means an extra 1.4MB memory being used during population). Next: fun with the 9i dictionary views.

    Read the article

  • Mac OS X Server Configure DHCP Options 66 and 67

    - by Paul Adams
    I need to configure Mountain Lion (10.8.2) OS X Server BOOTP to provide DHCP options 66 and 67 to provide PXE booting for PCs on my network. I have tried following the bootpd MAN pages, but they are not specific enough. I have also read conflicting information on the net, but nothing definitive for Mountain Lion DHCP. From bootpd man page: bootpd has a built-in type conversion table for many more options, mostly those specified in RFC 2132, and will try to convert from whatever type the option appears in the property list to the binary, packet format. For example, if bootpd knows that the type of the option is an IP address or list of IP addresses, it converts from the string form of the IP address to the binary, network byte order numeric value. If the type of the option is a numeric value, it converts from string, integer, or boolean, to the proper sized, network byte-order numeric value. Regardless of whether bootpd knows the type of the option or not, you can always specify the DHCP option using the data property list type <key>dhcp_option_128</key> <data> AAqV1Tzo </data> My TFTP server is 172.16.152.20 and the bootfile is pxelinux.0 I have edited /etc/bootpd.plist and added the following to the subnet dict: <key>dhcp_option_66</key> <data> LW4gLWUgrBCYFAo= </data> <key>dhcp_option_67</key> <data> LW4gLWUgcHhlbGludXguMAo= </data> According to the man page, the data elements are supposed to be Base64 encoded, but no matter what I try, I cannot get PXE clients to boot. I have tried encoding 172.16.152.20 using various methods: echo "172.16.152.20" | openssl enc -base64 returns MTcyLjE2LjE1Mi4yMAo= DHCP Option Code Utility (http://mac.softpedia.com/get/Internet-Utilities/DHCP-Option-Code-Utility.shtml) generating a string from 172.16.152.20 yields: LW4gLWUgMTcyLjE2LjE1Mi4yMAo= (used in the above example) DHCP Option Code Utility generating an IP Addresss from 172.16.152.20 yields: LW4gLWUgrBCYFAo= Encoding pxelinux.0 with the above methods likewise yields different encodings. I have tried using all three methods of encoding the data elements, but nothing seems to work i.e. my PXE boot clients do not get directed to my TFTP server. Can anyone help? Regards, Paul Adams.

    Read the article

  • XenServer 6.0.2 path to installation media contains non-ascii characters

    - by cmaduro
    XenServer 6.0.2 install fails no matter what I do. I have confirmed that the md5 checksum on my ISO file is good. I tried installing from a mounted ISO file (remotely via iKVM). I tried installing from physical media. I tried installing from a bootable USB stick (using syslinux + contents of the ISO) All attempts have yielded the same result: When verifying the installation media, at 0% initializing, the following is reported: "Some packages appeared to be damaged." followed by a list of pretty much all the gz2 and rpm packages. If I skip the media verification the installer proceeds and then gives me an error when it reaches "Installing from base pack" at 0% which states "An unrecoverable error has occurred. The error was: 'ascii' codec can't decode byte 0xff in position 20710: ordinal not in range(128) Please refer to your user guide, or contact a Technical Support Representative, for further details" there is one option left which is to reboot. Apparently at some point during the processing of the repositories on the installation media non-ascii characters are found, which causes the installer to quit. How do I fix this? Here are my specs TYAN S8236 motherboard 2 AMD Opteron 6234 processors LSI2008 card connected to 2 1TB Seagate Constellation drives SATA, 1 500GB Corsair m4 SSD SATA and 1 Corsair Forse 3 - 64GB SSD SATA Onboard SATA connected to a slim DVD-+RW. Onboard SAS connected to 2 IBM ESX 70GB 10K SAS drives (for XenServer) 256GB memory ================================================================================= Comments: According to pylonsbook.com "chances are you have run into a problem with character sets, encodings, and Unicode" – cmaduro 10 hours ago A clue is provided by "vmware.com/support/vsphere5/doc/…; Data migration fails if the path to the vCenter Server installation media contains non-ASCII characters When this problem occurs, an error message similar to: 'ascii' codec can't decode byte 0xd0 in position 30: ordinal not in range(128) appears, and the installer quits unexpectedly during the data migration process. – cmaduro 10 hours ago This is an error that python throws. And guess what, the .py extention of the file you have to edit in this link community.spiceworks.com/how_to/show/1168 means the installer is written in python. Python is interpreted, so now to find the install file responsible for this error. – cmaduro 6 hours ago The file that generates the error upon verification is /opt/xensource/installer/tui/repo.py. The error message appears around line 359. – cmaduro 2 hours ago I am fairly sure that the install error is generated somewhere in repository.py as the backend.py file throws errors while methods in that file are being called. Perhaps all errors can be traced back to this file. – cmaduro 1 hour ago

    Read the article

  • Establishing Serial Port communication through USB in Linux

    - by Prashant Singh
    I am new to Ubuntu and I need to establish a serial port communication between my PC and microcontroller MSP430G2452. On connection the USB available with the Launchpad and using lsusb. It identifies the port as: Bus 005 Device 003: ID 0451:f432 Texas Instruments, Inc. eZ430 Development Tool After establishing such a connection what I need to do? My aim is to send a byte of information in Linux.

    Read the article

  • How to remove iso 9660 from USB?

    - by a_m0d
    I have somehow managed to write an iso 9660 image onto my USB drive, which makes all my computer think that the device is actually a CD. I have tried various methods of removing this partition, but nothing seems to work. I have tried fdisk, which says $ fdisk -l /dev/sdb Cannot open /dev/sdb parted crashes when I try to use it on this device. I have even tried $ dd if=/dev/zero of=/dev/sdb but it just hangs with no output (either on screen or on disk). However, when I plug the USB in, it does mount, and I can view (but not edit) the files on it. edit: now the result is $ dd if=/dev/zero of=/dev/sdb dd: opening `/dev/sdb': Read-only file system I have also tried re-formatting it on Windows, but it gets to the end of the format process and then says "Couldn't format the drive". How can I remove this partition and get my whole USB drive back to normal again? EDIT 1: Trying a simple mkfs doesn't work: $ sudo mkfs -t vfat /dev/sdb mkfs.vfat 3.0.0 (28 Sep 2008) mkfs.vfat: Will not try to make filesystem on full-disk device '/dev/sdb' (use -I if wanted) I can't do mkfs on /dev/sdb1 because there is no such partition, as shown:$ ls /dev | grep sdb sdb EDIT 2: This is the information posted by dmesg when I plug the device in:$ dmesg . . (snip) . usb 2-1: New USB device found, idVendor=058f, idProduct=6387 usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 usb 2-1: Product: Mass Storage usb 2-1: Manufacturer: Generic usb 2-1: SerialNumber: G0905000000000010885 usb-storage: device found at 4 usb-storage: waiting for device to settle before scanning usb-storage: device scan complete scsi 6:0:0:0: Direct-Access FLASH Drive AU_USB20 8.07 PQ: 0 ANSI: 2 sd 6:0:0:0: [sdb] 4069376 512-byte hardware sectors (2084 MB) sd 6:0:0:0: [sdb] Write Protect is off sd 6:0:0:0: [sdb] Mode Sense: 03 00 00 00 sd 6:0:0:0: [sdb] Assuming drive cache: write through sd 6:0:0:0: [sdb] 4069376 512-byte hardware sectors (2084 MB) sd 6:0:0:0: [sdb] Write Protect is off sd 6:0:0:0: [sdb] Mode Sense: 03 00 00 00 sd 6:0:0:0: [sdb] Assuming drive cache: write through sdb: unknown partition table sd 6:0:0:0: [sdb] Attached SCSI removable disk sd 6:0:0:0: Attached scsi generic sg2 type 0 ISO 9660 Extensions: Microsoft Joliet Level 3 ISO 9660 Extensions: RRIP_1991A SELinux: initialized (dev sdb, type iso9660), uses genfs_contexts CE: hpet increasing min_delta_ns to 15000 nsec This shows that the device is formatted as ISO 9660 and that it is /dev/sdb. EDIT 3: This is the message that I find at the bottom of dmesg after running cfdisk and writing a new partition table to the disk:SELinux: initialized (dev sdb, type iso9660), uses genfs_contexts sd 17:0:0:0: [sdb] Device not ready: Sense Key : Not Ready [current] sd 17:0:0:0: [sdb] Device not ready: < ASC=0xff ASCQ=0xffASC=0xff < ASCQ=0xff end_request: I/O error, dev sdb, sector 0 Buffer I/O error on device sdb, logical block 0 lost page write due to I/O error on sdb

    Read the article

  • Abnormal hangs and restarts Ubuntu 8.04

    - by jai-ho
    Hi, I am using Ubuntu 8.04 LTS and seeing the following behaviors: The system hangs after a while and becomes completely unresponsive. The system sometimes restarts itself ! Can you please help me identify what is the problem? Also please mention where should I look for the possible cause of this error. Thanks. EDIT: Got the following from the dmesg output (the system got hung and had to restart) [ 15.452015] Driver 'sr' needs updating - please use bus_type methods [ 15.456882] Driver 'sd' needs updating - please use bus_type methods [ 15.457987] sr0: scsi3-mmc drive: 52x/52x writer cd/rw xa/form2 cdda tray [ 15.457993] Uniform CD-ROM driver Revision: 3.20 [ 15.458058] sr 0:0:1:0: Attached scsi CD-ROM sr0 [ 15.463028] sd 1:0:0:0: [sda] 156301488 512-byte hardware sectors (80026 MB) [ 15.463051] sd 1:0:0:0: [sda] Write Protect is off [ 15.463055] sd 1:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 15.463083] sd 1:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 15.463151] sd 1:0:0:0: [sda] 156301488 512-byte hardware sectors (80026 MB) [ 15.463167] sd 1:0:0:0: [sda] Write Protect is off [ 15.463171] sd 1:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 15.463197] sd 1:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 15.463202] sda:<5sr 0:0:1:0: Attached scsi generic sg0 type 5 [ 15.464634] sd 1:0:0:0: Attached scsi generic sg1 type 0 [ 15.470120] sda1 sda2 < sda5 [ 15.495536] sd 1:0:0:0: [sda] Attached SCSI disk [ 15.759549] Attempting manual resume [ 15.759554] swsusp: Resume From Partition 8:5 [ 15.759556] PM: Checking swsusp image. [ 15.759742] PM: Resume from disk failed. [ 15.779964] EXT3-fs: INFO: recovery required on readonly filesystem. [ 15.779970] EXT3-fs: write access will be enabled during recovery. [ 19.904204] kjournald starting. Commit interval 5 seconds [ 19.904235] EXT3-fs: sda1: orphan cleanup on readonly fs [ 19.904245] ext3_orphan_cleanup: deleting unreferenced inode 303260 [ 19.904304] ext3_orphan_cleanup: deleting unreferenced inode 303329 [ 19.932763] ext3_orphan_cleanup: deleting unreferenced inode 3801871 [ 19.932785] ext3_orphan_cleanup: deleting unreferenced inode 3801874 [ 19.932798] ext3_orphan_cleanup: deleting unreferenced inode 3801910 [ 19.951253] ext3_orphan_cleanup: deleting unreferenced inode 3801912 [ 19.951266] ext3_orphan_cleanup: deleting unreferenced inode 3801914 [ 19.951278] ext3_orphan_cleanup: deleting unreferenced inode 3959212 [ 19.951299] ext3_orphan_cleanup: deleting unreferenced inode 3959213 [ 19.960335] ext3_orphan_cleanup: deleting unreferenced inode 3959215 [ 19.963531] ext3_orphan_cleanup: deleting unreferenced inode 3801875 [ 19.963545] ext3_orphan_cleanup: deleting unreferenced inode 3663727 [ 19.963565] ext3_orphan_cleanup: deleting unreferenced inode 3663708 [ 19.963577] ext3_orphan_cleanup: deleting unreferenced inode 4072122 [ 19.963597] ext3_orphan_cleanup: deleting unreferenced inode 4072157 [ 19.968616] ext3_orphan_cleanup: deleting unreferenced inode 4072159 [ 19.970252] ext3_orphan_cleanup: deleting unreferenced inode 4072160 [ 19.970264] ext3_orphan_cleanup: deleting unreferenced inode 4072161 [ 19.992889] ext3_orphan_cleanup: deleting unreferenced inode 4072264 [ 19.992903] ext3_orphan_cleanup: deleting unreferenced inode 4072267 [ 19.999585] ext3_orphan_cleanup: deleting unreferenced inode 4072268 [ 20.008329] ext3_orphan_cleanup: deleting unreferenced inode 4072270 [ 20.008343] ext3_orphan_cleanup: deleting unreferenced inode 4072123 [ 20.008360] ext3_orphan_cleanup: deleting unreferenced inode 4072452 [ 20.008374] ext3_orphan_cleanup: deleting unreferenced inode 4072453 [ 20.008385] ext3_orphan_cleanup: deleting unreferenced inode 4072124 [ 20.008398] ext3_orphan_cleanup: deleting unreferenced inode 311574 [ 20.008413] ext3_orphan_cleanup: deleting unreferenced inode 967890 [ 20.008420] EXT3-fs: sda1: 28 orphan inodes deleted [ 20.008423] EXT3-fs: recovery complete. [ 20.082622] EXT3-fs: mounted filesystem with ordered data mode. [ 29.025379] input: PC Speaker as /devices/platform/pcspkr/input/input2 [ 29.187133] Linux agpgart interface v0.102 [ 29.225338] iTCO_vendor_support: vendor-support=0 [ 29.259662] iTCO_wdt: Intel TCO WatchDog Timer Driver v1.02 (26-Jul-2007)

    Read the article

  • How to unlock and remove a protected partition from Prestigio USB stick?

    - by mr.b
    Ok, so, I have one of those fancy schmancy devices, which is given to me by a frustrated friend of mine. Device is a Prestigio Leather 8GB, which identifies itself to Linux host as: Bus 001 Device 006: ID 1307:0165 Transcend Information, Inc. 2GB/4GB Flash Drive Kernel messages as USB device is plugged in: kernel: [ 2769.580042] usb 1-9: new high speed USB device using ehci_hcd and address 7 kernel: [ 2769.714782] scsi8 : usb-storage 1-9:1.0 kernel: [ 2770.713937] scsi 8:0:0:0: Direct-Access 8192MB flash drive 1.00 PQ: 0 ANSI: 2 kernel: [ 2770.714535] scsi 8:0:0:1: Direct-Access 8192MB flash drive 1.00 PQ: 0 ANSI: 2 kernel: [ 2770.715734] sd 8:0:0:0: Attached scsi generic sg3 type 0 kernel: [ 2770.716108] sd 8:0:0:1: Attached scsi generic sg4 type 0 kernel: [ 2770.722175] sd 8:0:0:0: [sdc] 962560 512-byte logical blocks: (492 MB/470 MiB) kernel: [ 2770.722657] sd 8:0:0:0: [sdc] Write Protect is on kernel: [ 2770.731078] sd 8:0:0:1: [sdd] 14012416 512-byte logical blocks: (7.17 GB/6.68 GiB) kernel: [ 2770.731215] sdc: kernel: [ 2770.738251] sd 8:0:0:1: [sdd] Write Protect is off kernel: [ 2770.880328] kernel: [ 2770.885876] sd 8:0:0:0: [sdc] Attached SCSI removable disk kernel: [ 2770.887442] sdd: unknown partition table kernel: [ 2771.049605] sd 8:0:0:1: [sdd] Attached SCSI removable disk So, symptoms are typical for U3-like devices: two separate devices inside of a single flash device. Windows sees it also as two identical usb devices, and mounts two separate drives to system, whereas first one presents itself as a CDROM device, holding a write-protected content, and second is a regular flash-disk partition, that "can" be written to. However, it seems like it's broken in some weird way, since it won't let me write anything to it, format it, nothing, but that's not the issue right now. Question: How can I unlock entire USB stick so it appears to system as a single, 8GB device which can be partitioned and used normally, without restrictions? Since it appeared to be an U3 device, I have tried standard utilities: both U3 Uninstaller by u3.com (found on SoftPedia), and opensource u3_tool from sourceforge (on both Windows and Linux). First utility failed to even detect USB stick as U3 device (simply stood idle while I re-plugged stick several times), while second tool failed with some obscure error about SCSI command unable to do something (I might be able to provide exact errors when I switch back to windows). u3_tool -i /dev/sg3 (Display device info) fails with u3_partition_info() failed: Device reported command failed: status 1 ...and every other option fails with same error, minus first part which states which command precisely has failed. So, apparently, this isn't a U3 device. Or, if it is, it doesn't behave like one. I read on a few occasions that this device protection is done by special command sent to device which tells it to lock itself, and so there should be an unlock command, that would set drive straight. Does anyone have any idea about what could I do to this device to fix it? P.S. I also mentioned a problem with being unable to use second "drive", but I'll tackle that problem when (and if) I manage to merge those two devices into one...

    Read the article

  • is my touchpad dying? Gentoo Linux

    - by Walter White
    Hi all, My touchpad on my laptop appears to be no longer functioning. I typically use an external keyboard and mouse so I didn't notice the problem until I tried to use the touchpad. Even after toggling the on/off switch several times, the touchpad still doesn't work. In the logs, I see something about cannot read byte from synaptics device. I will post the full logs when I am in front of my machine. Thanks, Walter

    Read the article

  • 48-bit colours?

    - by grawity
    Quite often, especially in X11-related things (X resources, Roxterm themes, etc) I see colours specified as 48-byte numbers: #2e2e34343636, #cccc00000000 instead of the usual 24-bit #2e3436 and #cc0000. What are the extra bits used for?

    Read the article

  • Strange traceroute to msdn.microsoft.com

    - by Jasper
    The problem is I could not view any msdn.microsoft.com/* site and the main site itself on my Ubuntu box on Google Chrome browser. Error is: Error 101 (net::ERR_CONNECTION_RESET): The connection was reset. When I run traceout I get different result: Here is simple one: traceroute msdn.microsoft.com traceroute to msdn.microsoft.com (65.55.11.235), 30 hops max, 60 byte packets 1 10.0.0.138 (10.0.0.138) 0.121 ms 0.131 ms 0.128 ms 2 192.168.0.1 (192.168.0.1) 1.730 ms 1.724 ms 2.024 ms 3 bzq-179-37-1.static.bezeqint.net (212.179.37.1) 18.314 ms 19.277 ms 20.694 ms 4 bzq-218-227-250.red.bezeqint.net (81.218.227.250) 22.806 ms 23.651 ms 24.820 ms 5 bzq-179-75-198.static.bezeqint.net (212.179.75.198) 26.650 ms 27.533 ms 28.791 ms 6 * * * 7 bzq-179-124-122.static.bezeqint.net (212.179.124.122) 76.032 ms 72.968 ms 74.660 ms 8 igblmdistc7504.uk.msft.net (195.66.224.140) 75.708 ms 76.797 ms 78.257 ms 9 ge-5-1-0-0.lts-64cb-1a.ntwk.msn.net (207.46.42.227) 80.125 ms 81.336 ms 82.671 ms 10 ge-7-0-0-0.nyc-64cb-1a.ntwk.msn.net (207.46.47.20) 179.232 ms so-7-1-0-0.ash-64cb-1b.ntwk.msn.net (213.199.144.158) 162.508 ms 163.223 ms 11 xe-0-0-1-0.co1-96c-1b.ntwk.msn.net (207.46.45.29) 227.964 ms ge-7-0-0-0.co1-64c-1b.ntwk.msn.net (207.46.40.90) 228.226 ms xe-0-0-1-0.co1-96c-1b.ntwk.msn.net (207.46.45.29) 212.781 ms 12 10.22.8.54 (10.22.8.54) 215.046 ms xe-5-2-0-0.co1-96c-1a.ntwk.msn.net (207.46.40.167) 214.825 ms 10.22.8.58 (10.22.8.58) 213.251 ms 13 10.22.8.62 (10.22.8.62) 212.745 ms 213.827 ms 10.22.8.50 (10.22.8.50) 215.655 ms 14 10.22.8.62 (10.22.8.62) 211.665 ms !X 10.22.8.50 (10.22.8.50) 214.491 ms !X 10.22.8.54 (10.22.8.54) 218.471 ms !X Line 1,2 : It's me Line from 3-7: It's my Internet provider Line 8 and on: I think I hit MS servers WTF line 12-14 ????? 10.22.8.x ???? then I run this traceroute: sudo traceroute -T msdn.microsoft.com traceroute to msdn.microsoft.com (65.55.11.235), 30 hops max, 60 byte packets 1 10.0.0.138 (10.0.0.138) 0.109 ms 0.127 ms * 2 * * * 3 * * * 4 * * * 5 * * * 6 * 65.55.11.235 (65.55.11.235) 16.019 ms 17.364 ms So I hit MSDN web site already at 6 hop ! WTF ??? This is host -a msdn.microsoft.com from me: host -a msdn.microsoft.com Trying "msdn.microsoft.com" ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19522 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;msdn.microsoft.com. IN ANY ;; ANSWER SECTION: msdn.microsoft.com. 3274 IN CNAME msdn.microsoft.akadns.net. msdn.microsoft.akadns.net. 600 IN A 65.55.11.235 Received 91 bytes from 127.0.0.1#53 in 108 ms Could someone help me understand and fix it ??

    Read the article

  • mounting ext4 fs with block size of 65536

    - by seaquest
    I am doing some benchmarking on EXT4 performance on Compact Flash media. I have created an ext4 fs with block size of 65536. however I can not mount it on ubuntu-10.10-netbook-i386. (it is already mounting ext4 fs with 4096 bytes of block sizes) According to my readings on ext4 it should allow such big block sized fs. I want to hear your comments. root@ubuntu:~# mkfs.ext4 -b 65536 /dev/sda3 Warning: blocksize 65536 not usable on most systems. mke2fs 1.41.12 (17-May-2010) mkfs.ext4: 65536-byte blocks too big for system (max 4096) Proceed anyway? (y,n) y Warning: 65536-byte blocks too big for system (max 4096), forced to continue Filesystem label= OS type: Linux Block size=65536 (log=6) Fragment size=65536 (log=6) Stride=0 blocks, Stripe width=0 blocks 19968 inodes, 19830 blocks 991 blocks (5.00%) reserved for the super user First data block=0 1 block group 65528 blocks per group, 65528 fragments per group 19968 inodes per group Writing inode tables: done Creating journal (1024 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 37 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. root@ubuntu:~# tune2fs -l /dev/sda3 tune2fs 1.41.12 (17-May-2010) Filesystem volume name: <none> Last mounted on: <not available> Filesystem UUID: 4cf3f507-e7b4-463c-be11-5b408097099b Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags: signed_directory_hash Default mount options: (none) Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 19968 Block count: 19830 Reserved block count: 991 Free blocks: 18720 Free inodes: 19957 First block: 0 Block size: 65536 Fragment size: 65536 Blocks per group: 65528 Fragments per group: 65528 Inodes per group: 19968 Inode blocks per group: 78 Flex block group size: 16 Filesystem created: Sat Feb 5 14:39:55 2011 Last mount time: n/a Last write time: Sat Feb 5 14:40:02 2011 Mount count: 0 Maximum mount count: 37 Last checked: Sat Feb 5 14:39:55 2011 Check interval: 15552000 (6 months) Next check after: Thu Aug 4 14:39:55 2011 Lifetime writes: 70 MB Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 28 Desired extra isize: 28 Journal inode: 8 Default directory hash: half_md4 Directory Hash Seed: afb5b570-9d47-4786-bad2-4aacb3b73516 Journal backup: inode blocks root@ubuntu:~# mount -t ext4 /dev/sda3 /mnt/ mount: wrong fs type, bad option, bad superblock on /dev/sda3, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so

    Read the article

  • can't use periods in ServerName [Lion Apache installation]

    - by punchfacechamp
    I can access my host like this… http://keggyshop but can't use periods… http://keggyshop.dev here's my virtual host directive… <VirtualHost *:80> ServerName keggyshop ServerAlias keggyshop.dev DocumentRoot "~/sites/2012/keggy/web/pages/keggy/120528/sandbox/public" <Directory "~/sites/2012/keggy/web/pages/keggy/120528/sandbox/public"> Options Includes FollowSymLinks AllowOverride All Order allow,deny Allow from all </Directory> </VirtualHost> host file 127.0.0.1 keggyshop 127.0.0.1 keggyshop.dev traceroute for keggyshop… user$ traceroute keggyshop traceroute to keggyshop (192.168.1.184), 64 hops max, 52 byte packets 1 keggyshop (192.168.1.184) 1.188 ms 0.683 ms 0.747 ms traceroute for keggyshop.dev… user$ traceroute keggyshop.dev traceroute: Warning: keggyshop.dev has multiple addresses; using 184.106.15.239 traceroute to keggyshop.dev (184.106.15.239), 64 hops max, 52 byte packets 1 * 192.168.1.1 (192.168.1.1) 0.856 ms 0.568 ms 2 10.81.192.1 (10.81.192.1) 15.232 ms 7.002 ms 7.936 ms 3 gig-0-3-0-6-nycmnya-rtr2.nyc.rr.com (24.29.97.122) 7.962 ms 7.813 ms 7.712 ms 4 bun101.nycmnytg-rtr001.nyc.rr.com (184.152.112.107) 10.999 ms 14.001 ms 15.466 ms 5 bun6-nycmnytg-rtr002.nyc.rr.com (24.29.148.250) 11.231 ms 17.321 ms 12.745 ms 6 107.14.19.24 (107.14.19.24) 13.972 ms 11.704 ms 16.477 ms 7 ae-1-0.pr0.nyc30.tbone.rr.com (66.109.6.161) 9.237 ms 11.896 ms 107.14.19.153 (107.14.19.153) 7.481 ms 8 xe-5-0-6.ar2.ewr1.us.nlayer.net (69.31.94.57) 16.682 ms 11.791 ms 11.981 ms 9 ae3-90g.cr1.ewr1.us.nlayer.net (69.31.94.117) 12.977 ms 15.706 ms 9.709 ms 10 xe-5-0-0.cr1.ord1.us.nlayer.net (69.22.142.74) 30.473 ms 30.497 ms 31.750 ms 11 ae1-20g.ar1.ord6.us.nlayer.net (69.31.110.250) 36.699 ms 50.785 ms 35.957 ms 12 as19994.xe-1-0-7.ar1.ord6.us.nlayer.net (69.31.110.242) 34.723 ms 31.118 ms 29.967 ms 13 coreb.ord1.rackspace.net (184.106.126.138) 30.471 ms corea.ord1.rackspace.net (184.106.126.136) 33.392 ms 35.210 ms 14 core1-coreb.ord1.rackspace.net (184.106.126.129) 32.453 ms core1-corea.ord1.rackspace.net (184.106.126.125) 32.020 ms core1-coreb.ord1.rackspace.net (184.106.126.129) 32.417 ms 15 core1-aggr401a-3.ord1.rackspace.net (173.203.0.157) 31.274 ms 34.854 ms 30.194 ms

    Read the article

  • psybnc on nas: ncurses problem

    - by holms
    Trying to get compile psybnc on NAS. ipkg is default package manager in here. I've installed ncurses already, it's in /opt/lib (libncurses.so) [\w] # ls /opt/lib | grep ncurses libncurses.so libncurses.so.5 libncurses.so.5.7 libncursesw.so libncursesw.so.5 libncursesw.so.5.7 [\w] # file libncurses.so.5.7 libncurses.so.5.7: ELF 32-bit LSB shared object, ARM, version 1 (SYSV), dynamically linked, stripped I added this path to /etc/profile [\w] # echo $PATH /bin:/sbin:/usr/bin:/usr/sbin:/opt/bin:/opt/sbin:/opt/lib So trying to make menuconfig gives me this error [\w] # make menuconfig Initializing Menu-Configuration [*] Running Conversion Tool for older psyBNC Data. Using existent configuration File. [*] Running Autoconfig. System: Linux Socket Libs: Internal. Environment: Internal. Time-Headers: in time.h and sys/time.h Byte order: Big Endian. IPv6-Support: Yes, general support. But no interface configured. async-DNS-Support: Yes. SSL-Support: No openssl found. Get openssl at www.openssl.org Creating Makefile [*] Creating Menu, please wait. This needs the ncurses library. If it is not available, menuconf wont work. If you are using curses, use make menuconfig-curses instead. make: *** [menuconfig] Error 1 Same goes for make menuconfig-curses [\w] # make menuconfig-curses Initializing Menu-Configuration using Curses [*] Running Conversion Tool for older psyBNC Data. Using existent configuration File. [*] Running Autoconfig. System: Linux Socket Libs: Internal. Environment: Internal. Time-Headers: in time.h and sys/time.h Byte order: Big Endian. IPv6-Support: Yes, general support. But no interface configured. async-DNS-Support: Yes. SSL-Support: No openssl found. Get openssl at www.openssl.org Creating Makefile [*] Creating Menu, please wait. This needs the curses library. If it is not available, menuconf wont work. make: *** [menuconfig-curses] Error 1 Psybnc compiled ok, just wanna work with menuconfig instead of configuration file.

    Read the article

  • squid cache disk configuration

    - by Gogonez
    just wondering how far drive configuration will affect squid cache performance. what kind of drive configuration that fast enough for squid ? is it true that block-level parity strip raid faster than byte-level one ? is mirrored drive config will decrease squid cache write process ? how much swap space that squid realy need to store cache (reverse mode) for 200mb web doc ? what kind of benchmark should i do to analyze squid disk performance ?

    Read the article

  • e2fsck extremely slow, although enough memory exists

    - by kaefert
    I've got this external USB-Disk: kaefert@blechmobil:~$ lsusb -s 2:3 Bus 002 Device 003: ID 0bc2:3320 Seagate RSS LLC As can be seen in this dmesg output, there is some problem that prevents that disk from beeing mounted: kaefert@blechmobil:~$ dmesg ... [ 113.084079] usb 2-1: new high-speed USB device number 3 using ehci_hcd [ 113.217783] usb 2-1: New USB device found, idVendor=0bc2, idProduct=3320 [ 113.217787] usb 2-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1 [ 113.217790] usb 2-1: Product: Expansion Desk [ 113.217792] usb 2-1: Manufacturer: Seagate [ 113.217794] usb 2-1: SerialNumber: NA4J4N6K [ 113.435404] usbcore: registered new interface driver uas [ 113.455315] Initializing USB Mass Storage driver... [ 113.468051] scsi5 : usb-storage 2-1:1.0 [ 113.468180] usbcore: registered new interface driver usb-storage [ 113.468182] USB Mass Storage support registered. [ 114.473105] scsi 5:0:0:0: Direct-Access Seagate Expansion Desk 070B PQ: 0 ANSI: 6 [ 114.474342] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.475089] sd 5:0:0:0: [sdb] Write Protect is off [ 114.475092] sd 5:0:0:0: [sdb] Mode Sense: 43 00 00 00 [ 114.475959] sd 5:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 114.477093] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.501649] sdb: sdb1 [ 114.502717] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.504354] sd 5:0:0:0: [sdb] Attached SCSI disk [ 116.804408] EXT4-fs (sdb1): ext4_check_descriptors: Checksum for group 3976 failed (47397!=61519) [ 116.804413] EXT4-fs (sdb1): group descriptors corrupted! ... So I went and fired up my favorite partition manager - gparted, and told it to verify and repair the partition sdb1. This made gparted call e2fsck (version 1.42.4 (12-Jun-2012)) e2fsck -f -y -v /dev/sdb1 Although gparted called e2fsck with the "-v" option, sadly it doesn't show me the output of my e2fsck process (bugreport https://bugzilla.gnome.org/show_bug.cgi?id=467925 ) I started this whole thing on Sunday (2012-11-04_2200) evening, so about 48 hours ago, this is what htop says about it now (2012-11-06-1900): PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command 3704 root 39 19 1560M 1166M 768 R 98.0 19.5 42h56:43 e2fsck -f -y -v /dev/sdb1 Now I found a few posts on the internet that discuss e2fsck running slow, for example: http://gparted-forum.surf4.info/viewtopic.php?id=13613 where they write that its a good idea to see if the disk is just that slow because maybe its damaged, and I think these outputs tell me that this is not the case in my case: kaefert@blechmobil:~$ sudo hdparm -tT /dev/sdb /dev/sdb: Timing cached reads: 3562 MB in 2.00 seconds = 1783.29 MB/sec Timing buffered disk reads: 82 MB in 3.01 seconds = 27.26 MB/sec kaefert@blechmobil:~$ sudo hdparm /dev/sdb /dev/sdb: multcount = 0 (off) readonly = 0 (off) readahead = 256 (on) geometry = 364801/255/63, sectors = 5860533160, start = 0 However, although I can read quickly from that disk, this disk speed doesn't seem to be used by e2fsck, considering tools like gkrellm or iotop or this: kaefert@blechmobil:~$ iostat -x Linux 3.2.0-2-amd64 (blechmobil) 2012-11-06 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 14,24 47,81 14,63 0,95 0,00 22,37 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sda 0,59 8,29 2,42 5,14 43,17 160,17 53,75 0,30 39,80 8,72 54,42 3,95 2,99 sdb 137,54 5,48 9,23 0,20 587,07 22,73 129,35 0,07 7,70 7,51 16,18 2,17 2,04 Now I researched a little bit on how to find out what e2fsck is doing with all that processor time, and I found the tool strace, which gives me this: kaefert@blechmobil:~$ sudo strace -p3704 lseek(4, 41026998272, SEEK_SET) = 41026998272 write(4, "\212\354K[_\361\3nl\212\245\352\255jR\303\354\312Yv\334p\253r\217\265\3567\325\257\3766"..., 4096) = 4096 lseek(4, 48404766720, SEEK_SET) = 48404766720 read(4, "\7t\260\366\346\337\304\210\33\267j\35\377'\31f\372\252\ffU\317.y\211\360\36\240c\30`\34"..., 4096) = 4096 lseek(4, 41027002368, SEEK_SET) = 41027002368 write(4, "\232]7Ws\321\352\t\1@[+5\263\334\276{\343zZx\352\21\316`1\271[\202\350R`"..., 4096) = 4096 lseek(4, 48404770816, SEEK_SET) = 48404770816 read(4, "\17\362r\230\327\25\346//\210H\v\311\3237\323K\304\306\361a\223\311\324\272?\213\tq \370\24"..., 4096) = 4096 lseek(4, 41027006464, SEEK_SET) = 41027006464 write(4, "\367yy>x\216?=\324Z\305\351\376&\25\244\210\271\22\306}\276\237\370(\214\205G\262\360\257#"..., 4096) = 4096 lseek(4, 48404774912, SEEK_SET) = 48404774912 read(4, "\365\25\0\21|T\0\21}3t_\272\373\222k\r\177\303\1\201\261\221$\261B\232\3142\21U\316"..., 4096) = 4096 ^CProcess 3704 detached around 16 of these lines every second, so 4 read and 4 write operations every second, which I don't consider to be a lot.. And finally, my question: Will this process ever finish? If those numbers from fseek (48404774912) represent bytes, that would be something like 45 gigabytes, with this beeing a 3 terrabyte disk, which would give me 134 days to go, if the speed stays constant, and e2fsck scans the disk like this completly and only once. Do you have some advice for me? I have most of the data on that disk elsewhere, but I've put a lot of hours into sorting and merging it to this disk, so I would prefer to getting this disk up and running again, without formatting it anew. I don't think that the hardware is damaged since the disk is only a few months and since I can't see any I/O errors in the dmesg output. UPDATE: I just looked at the strace output again (2012-11-06_2300), now it looks like this: lseek(4, 1419860611072, SEEK_SET) = 1419860611072 read(4, "3#\f\2447\335\0\22A\355\374\276j\204'\207|\217V|\23\245[\7VP\251\242\276\207\317:"..., 4096) = 4096 lseek(4, 43018145792, SEEK_SET) = 43018145792 write(4, "]\206\231\342Y\204-2I\362\242\344\6R\205\361\324\177\265\317C\334V\324\260\334\275t=\10F."..., 4096) = 4096 lseek(4, 1419860615168, SEEK_SET) = 1419860615168 read(4, "\262\305\314Y\367\37x\326\245\226\226\320N\333$s\34\204\311\222\7\315\236\336\300TK\337\264\236\211n"..., 4096) = 4096 lseek(4, 43018149888, SEEK_SET) = 43018149888 write(4, "\271\224m\311\224\25!I\376\16;\377\0\223H\25Yd\201Y\342\r\203\271\24eG<\202{\373V"..., 4096) = 4096 lseek(4, 1419860619264, SEEK_SET) = 1419860619264 read(4, ";d\360\177\n\346\253\210\222|\250\352T\335M\33\260\320\261\7g\222P\344H?t\240\20\2548\310"..., 4096) = 4096 lseek(4, 43018153984, SEEK_SET) = 43018153984 write(4, "\360\252j\317\310\251G\227\335{\214`\341\267\31Y\202\360\v\374\307oq\3063\217Z\223\313\36D\211"..., 4096) = 4096 So the numbers in the lseek lines before the reads, like 1419860619264 are already a lot bigger, standing for 1.29 terabytes if those numbers are bytes, so it doesn't seem to be a linear progress on a big scale, maybe there are only some areas that need work, that have big gaps in between them. UPDATE2: Okey, big disappointment, the numbers are back to very small again (2012-11-07_0720) lseek(4, 52174548992, SEEK_SET) = 52174548992 read(4, "\374\312\22\\\325\215\213\23\0357U\222\246\370v^f(\312|f\212\362\343\375\373\342\4\204mU6"..., 4096) = 4096 lseek(4, 46603526144, SEEK_SET) = 46603526144 write(4, "\370\261\223\227\23?\4\4\217\264\320_Am\246CQ\313^\203U\253\274\204\277\2564n\227\177\267\343"..., 4096) = 4096 so either e2fsck goes over the data multiple times, or it just hops back and forth multiple times. Or my assumption that those numbers are bytes is wrong. UPDATE3: Since it's mentioned here http://forums.fedoraforum.org/showthread.php?t=282125&page=2 that you can testisk while e2fsck is running, i tried that, though not with a lot of success. When asking testdisk to display the data of my partition, this is what I get: TestDisk 6.13, Data Recovery Utility, November 2011 Christophe GRENIER <[email protected]> http://www.cgsecurity.org 1 P Linux 0 4 5 45600 40 8 732566272 Can't open filesystem. Filesystem seems damaged. And this is what strace currently gives me (2012-11-07_1030) lseek(4, 212460343296, SEEK_SET) = 212460343296 read(4, "\315Mb\265v\377Gn \24\f\205EHh\2349~\330\273\203\3375\206\10\r3=W\210\372\352"..., 4096) = 4096 lseek(4, 47347830784, SEEK_SET) = 47347830784 write(4, "]\204\223\300I\357\4\26\33+\243\312G\230\250\371*m2U\t_\215\265J \252\342Pm\360D"..., 4096) = 4096 (times are in CET)

    Read the article

  • How can I set up a load balancer to direct all Search Engine Bot traffic to one server?

    - by Ryan
    We have a simple load balancer set up on Rackspace to 3 web server nodes. After reviewing our traffic and expenses, the largest bandwidth hog is Google Bot. Since on Rackspace we pay for bandwidth by the byte, we'd like to direct all traffic from GoogleBot to another host (MediaTemple) with unlimited bandwidth. We think this would cut our hosting bill several thousand dollars a month. Is this possible? Advisable?

    Read the article

  • How do I prevent TCP connection freezes over an OpenVPN network?

    - by Jason R
    New details added at the end of this question; it's possible that I'm zeroing in on the cause. I have a UDP OpenVPN-based VPN set up in tap mode (I need tap because I need the VPN to pass multicast packets, which doesn't seem to be possible with tun networks) with a handful of clients across the Internet. I've been experiencing frequent TCP connection freezes over the VPN. That is, I will establish a TCP connection (e.g. an SSH connection, but other protocols have similar issues), and at some point during the session, it seems that traffic will cease being transmitted over that TCP session. This seems to be related to points at which large data transfers occur, such as if I execute an ls command in an SSH session, or if I cat a long log file. Some Google searches turn up a number of answers like this previous one on Server Fault, indicating that the likely culprit is an MTU issue: that during periods of high traffic, the VPN is trying to send packets that get dropped somewhere in the pipes between the VPN endpoints. The above-linked answer suggests using the following OpenVPN configuration settings to mitigate the problem: fragment 1400 mssfix This should limit the MTU used on the VPN to 1400 bytes and fix the TCP maximum segment size to prevent the generation of any packets larger than that. This seems to mitigate the problem a bit, but I still frequently see the freezes. I've tried a number of sizes as arguments to the fragment directive: 1200, 1000, 576, all with similar results. I can't think of any strange network topology between the two ends that could trigger such a problem: the VPN server is running on a pfSense machine connected directly to the Internet, and my client is also connected directly to the Internet at another location. One other strange piece of the puzzle: if I run the tracepath utility, then that seems to band-aid the problem. A sample run looks like: [~]$ tracepath -n 192.168.100.91 1: 192.168.100.90 0.039ms pmtu 1500 1: 192.168.100.91 40.823ms reached 1: 192.168.100.91 19.846ms reached Resume: pmtu 1500 hops 1 back 64 The above run is between two clients on the VPN: I initiated the trace from 192.168.100.90 to the destination of 192.168.100.91. Both clients were configured with fragment 1200; mssfix; in an attempt to limit the MTU used on the link. The above results would seem to suggest that tracepath was able to detect a path MTU of 1500 bytes between the two clients. I would assume that it would be somewhat smaller due to the fragmentation settings specified in the OpenVPN configuration. I found that result somewhat strange. Even stranger, however: if I have a TCP connection in the stalled state (e.g. an SSH session with a directory listing that froze in the middle), then executing the tracepath command shown above causes the connection to start up again! I can't figure out any reasonable explanation for why this would be the case, but I feel like this might be pointing toward a solution to ultimately eradicate the problem. Does anyone have any recommendations for other things to try? Edit: I've come back and looked at this a bit further, and have found only more confounding information: I set the OpenVPN connection to fragment at 1400 bytes, as shown above. Then, I connected to the VPN from across the Internet and used Wireshark to look at the UDP packets that were sent to the VPN server while the stall occurred. None were greater than the specified 1400 byte count, so the fragmentation seems to be functioning properly. To verify that even a 1400-byte MTU would be sufficient, I pinged the VPN server using the following (Linux) command: ping <host> -s 1450 -M do This (I believe) sends a 1450-byte packet with fragmentation disabled (I at least verified that it didn't work if I set it to an obviously-too-large value like 1600 bytes). These seem to work just fine; I get replies back from the host with no issue. So, maybe this isn't an MTU issue at all. I'm just confused as to what else it might be! Edit 2: The rabbit hole just keeps getting deeper: I've now isolated the problem a bit more. It seems to be related to the exact OS that the VPN client uses. I have successfully duplicated the problem on at least three Ubuntu machines (versions 12.04 through 13.04). I can reliably duplicate an SSH connection freeze within a minute or so by just cat-ing a large log file. However, if I do the same test using a CentOS 6 machine as a client, then I don't see the problem! I've tested using the exact same OpenVPN client version as I was using on the Ubuntu machines. I can cat log files for hours without seeing the connection freeze. This seems to provide some insight as to the ultimate cause, but I'm just not sure what that insight is. I have examined the traffic over the VPN using Wireshark. I'm not a TCP expert, so I'm not sure what to make of the gory details, but the gist is that at some point, a UDP packet gets dropped due to the limited bandwidth of the Internet link, causing TCP retransmissions inside the VPN tunnel. On the CentOS client, these retransmissions occur properly and things move on happily. At some point with the Ubuntu clients, though, the remote end starts retransmitting the same TCP segment over and over (with the transmit delay increasing between each retransmission). The client sends what looks like a valid TCP ACK to each retransmission, but the remote end still continues to transmit the same TCP segment periodically. This extends ad infinitum and the connection stalls. My question here would be: Does anyone have any recommendations for how to troubleshoot and/or determine the root cause of the TCP issue? It's as if the remote end isn't accepting the ACK messages sent by the VPN client. One common difference between the CentOS node and the various Ubuntu releases is that Ubuntu has a much more recent Linux kernel version (from 3.2 in Ubuntu 12.04 to 3.8 in 13.04). A pointer to some new kernel bug maybe? I'm assuming that if that were so, then I wouldn't be the only one experiencing the problem; I don't think this seems like a particularly exotic setup.

    Read the article

  • Emacs mode is being applied with the delay

    - by Sergey
    I am trying to use Emacs for developing in Lua, and installed a Lua mode for that. After doing this I was unhappy about the background and changed it by applying the face of my text mode (which I configred by myself). It worked, but now the modified settings for Lua mode are being applied with the significant delay (3-5 sec) after opening a Lua file. Both .emacs and lua-mode.el are byte-compiled. Any advice?

    Read the article

  • Hide non printable characters in vim

    - by knittl
    Vim shows non-printable characters prefixed with a ^ (for instance ^@ for a NUL byte). I have a column based file containing both printable and non-printable characters which is difficult to read, since each non-printable character shifts all remaining columns one character to the right. Is there a way to hide non-printable characters or simply display a placeholder char instead? I also don't mind having every character be represented by two characters.

    Read the article

  • Bit-shifting a file

    - by mykhal
    I wonder if there is an utility to read and print a (binary) file, shifted by some amount of bits (i mean, it should accept amounts, which are not divisible by 8). .. something like dd (and its skip option), but bit-wise, instead of byte-wise. (If you think that there is no such thing, and are going to implement it here, please use C.. i have my own bit-shifting thing for strings, written in Python, but it is surely relatively slow as hell)

    Read the article

< Previous Page | 188 189 190 191 192 193 194 195 196 197 198 199  | Next Page >