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• General monitoring for SQL Server Analysis Services using Performance Monitor

  - by Testas

  A recent customer engagement required a setup of a monitoring solution for SSAS, due to the time restrictions placed upon this, native Windows Performance Monitor (Perfmon) and SQL Server Profiler Monitoring Tools was used as using a third party tool would have meant the customer providing an additional monitoring server that was not available.I wanted to outline the performance monitoring counters that was used to monitor the system on which SSAS was running. Due to the slow query performance that was occurring during certain scenarios, perfmon was used to establish if any pressure was being placed on the Disk, CPU or Memory subsystem when concurrent connections access the same query, and Profiler to pinpoint how the query was being managed within SSAS, profiler I will leave for another blogThis guide is not designed to provide a definitive list of what should be used when monitoring SSAS, different situations may require the addition or removal of counters as presented by the situation. However I hope that it serves as a good basis for starting your monitoring of SSAS. I would also like to acknowledge Chris Webb’s awesome chapters from “Expert Cube Development” that also helped shape my monitoring strategy:http://cwebbbi.spaces.live.com/blog/cns!7B84B0F2C239489A!6657.entrySimulating ConnectionsTo simulate the additional connections to the SSAS server whilst monitoring, I used ascmd to simulate multiple connections to the typical and worse performing queries that were identified by the customer. A similar sript can be downloaded from codeplex at http://www.codeplex.com/SQLSrvAnalysisSrvcs.     File name: ASCMD_StressTestingScripts.zip. Performance MonitorWithin performance monitor,  a counter log was created that contained the list of counters below. The important point to note when running the counter log is that the RUN AS property within the counter log properties should be changed to an account that has rights to the SSAS instance when monitoring MSAS counters. Failure to do so means that the counter log runs under the system account, no errors or warning are given while running the counter log, and it is not until you need to view the MSAS counters that they will not be displayed if run under the default account that has no right to SSAS. If your connection simulation takes hours, this could prove quite frustrating if not done beforehand JThe counters used……  Object Counter Instance Justification System Processor Queue legnth N/A Indicates how many threads are waiting for execution against the processor. If this counter is consistently higher than around 5 when processor utilization approaches 100%, then this is a good indication that there is more work (active threads) available (ready for execution) than the machine's processors are able to handle. System Context Switches/sec N/A Measures how frequently the processor has to switch from user- to kernel-mode to handle a request from a thread running in user mode. The heavier the workload running on your machine, the higher this counter will generally be, but over long term the value of this counter should remain fairly constant. If this counter suddenly starts increasing however, it may be an indicating of a malfunctioning device, especially if the Processor\Interrupts/sec\(_Total) counter on your machine shows a similar unexplained increase Process % Processor Time sqlservr Definately should be used if Processor\% Processor Time\(_Total) is maxing at 100% to assess the effect of the SQL Server process on the processor Process % Processor Time msmdsrv Definately should be used if Processor\% Processor Time\(_Total) is maxing at 100% to assess the effect of the SQL Server process on the processor Process Working Set sqlservr If the Memory\Available bytes counter is decreaing this counter can be run to indicate if the process is consuming larger and larger amounts of RAM. Process(instance)\Working Set measures the size of the working set for each process, which indicates the number of allocated pages the process can address without generating a page fault. Process Working Set msmdsrv If the Memory\Available bytes counter is decreaing this counter can be run to indicate if the process is consuming larger and larger amounts of RAM. Process(instance)\Working Set measures the size of the working set for each process, which indicates the number of allocated pages the process can address without generating a page fault. Processor % Processor Time _Total and individual cores measures the total utilization of your processor by all running processes. If multi-proc then be mindful only an average is provided Processor % Privileged Time _Total To see how the OS is handling basic IO requests. If kernel mode utilization is high, your machine is likely underpowered as it's too busy handling basic OS housekeeping functions to be able to effectively run other applications. Processor % User Time _Total To see how the applications is interacting from a processor perspective, a high percentage utilisation determine that the server is dealing with too many apps and may require increasing thje hardware or scaling out Processor Interrupts/sec _Total  The average rate, in incidents per second, at which the processor received and serviced hardware interrupts. Shoulr be consistant over time but a sudden unexplained increase could indicate a device malfunction which can be confirmed using the System\Context Switches/sec counter Memory Pages/sec N/A Indicates the rate at which pages are read from or written to disk to resolve hard page faults. This counter is a primary indicator of the kinds of faults that cause system-wide delays, this is the primary counter to watch for indication of possible insufficient RAM to meet your server's needs. A good idea here is to configure a perfmon alert that triggers when the number of pages per second exceeds 50 per paging disk on your system. May also want to see the configuration of the page file on the Server Memory Available Mbytes N/A is the amount of physical memory, in bytes, available to processes running on the computer. if this counter is greater than 10% of the actual RAM in your machine then you probably have more than enough RAM. monitor it regularly to see if any downward trend develops, and set an alert to trigger if it drops below 2% of the installed RAM. Physical Disk Disk Transfers/sec for each physical disk If it goes above 10 disk I/Os per second then you've got poor response time for your disk. Physical Disk Idle Time _total If Disk Transfers/sec is above  25 disk I/Os per second use this counter. which measures the percent time that your hard disk is idle during the measurement interval, and if you see this counter fall below 20% then you've likely got read/write requests queuing up for your disk which is unable to service these requests in a timely fashion. Physical Disk Disk queue legnth For the OLAP and SQL physical disk A value that is consistently less than 2 means that the disk system is handling the IO requests against the physical disk Network Interface Bytes Total/sec For the NIC Should be monitored over a period of time to see if there is anb increase/decrease in network utilisation Network Interface Current Bandwidth For the NIC is an estimate of the current bandwidth of the network interface in bits per second (BPS). MSAS 2005: Memory Memory Limit High KB N/A Shows (as a percentage) the high memory limit configured for SSAS in C:\Program Files\Microsoft SQL Server\MSAS10.MSSQLSERVER\OLAP\Config\msmdsrv.ini MSAS 2005: Memory Memory Limit Low KB N/A Shows (as a percentage) the low memory limit configured for SSAS in C:\Program Files\Microsoft SQL Server\MSAS10.MSSQLSERVER\OLAP\Config\msmdsrv.ini MSAS 2005: Memory Memory Usage KB N/A Displays the memory usage of the server process. MSAS 2005: Memory File Store KB N/A Displays the amount of memory that is reserved for the Cache. Note if total memory limit in the msmdsrv.ini is set to 0, no memory is reserved for the cache MSAS 2005: Storage Engine Query Queries from Cache Direct / sec N/A Displays the rate of queries answered from the cache directly MSAS 2005: Storage Engine Query Queries from Cache Filtered / Sec N/A Displays the Rate of queries answered by filtering existing cache entry. MSAS 2005: Storage Engine Query Queries from File / Sec N/A Displays the Rate of queries answered from files. MSAS 2005: Storage Engine Query Average time /query N/A Displays the average time of a query MSAS 2005: Connection Current connections N/A Displays the number of connections against the SSAS instance MSAS 2005: Connection Requests / sec N/A Displays the rate of query requests per second MSAS 2005: Locks Current Lock Waits N/A Displays thhe number of connections waiting on a lock MSAS 2005: Threads Query Pool job queue Length N/A The number of queries in the job queue MSAS 2005:Proc Aggregations Temp file bytes written/sec N/A Shows the number of bytes of data processed in a temporary file MSAS 2005:Proc Aggregations Temp file rows written/sec N/A Shows the number of bytes of data processed in a temporary file 

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• Sun Grid Engine: Automatically Terminating Idle Interactive Jobs

  - by dmcer

  We're considering using Sun Grid Engine on a small compute cluster. Right now, the current set up is pretty crude and just involves having people ssh to an open machine to run their jobs. We'd like to allow interactive jobs, since that should ease the transition from manually starting jobs to starting them using qsub. But, there is some concern that, if we do, people might accidentally leave their interactive sessions idle and block other jobs from being run on the machines. The issue isn't just theoretical, since we previously tried using OpenPBS and there was a problem with people opening up an interactive job in a screen session and essentially camping on a machine. Is there anyway to configure SGE to automatically kill idle interactive jobs? It looks like this was requested as an enhancement (Issue #:2447) way back in 2007. But, it doesn't seem like the request ever got implemented.

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• Fun with Aggregates

  - by Paul White

  There are interesting things to be learned from even the simplest queries.  For example, imagine you are given the task of writing a query to list AdventureWorks product names where the product has at least one entry in the transaction history table, but fewer than ten. One possible query to meet that specification is: SELECT p.Name FROM Production.Product AS p JOIN Production.TransactionHistory AS th ON p.ProductID = th.ProductID GROUP BY p.ProductID, p.Name HAVING COUNT_BIG(*) < 10; That query correctly returns 23 rows (execution plan and data sample shown below): The execution plan looks a bit different from the written form of the query: the base tables are accessed in reverse order, and the aggregation is performed before the join.  The general idea is to read all rows from the history table, compute the count of rows grouped by ProductID, merge join the results to the Product table on ProductID, and finally filter to only return rows where the count is less than ten. This ‘fully-optimized’ plan has an estimated cost of around 0.33 units.  The reason for the quote marks there is that this plan is not quite as optimal as it could be – surely it would make sense to push the Filter down past the join too?  To answer that, let’s look at some other ways to formulate this query.  This being SQL, there are any number of ways to write logically-equivalent query specifications, so we’ll just look at a couple of interesting ones.  The first query is an attempt to reverse-engineer T-SQL from the optimized query plan shown above.  It joins the result of pre-aggregating the history table to the Product table before filtering: SELECT p.Name FROM ( SELECT th.ProductID, cnt = COUNT_BIG(*) FROM Production.TransactionHistory AS th GROUP BY th.ProductID ) AS q1 JOIN Production.Product AS p ON p.ProductID = q1.ProductID WHERE q1.cnt < 10; Perhaps a little surprisingly, we get a slightly different execution plan: The results are the same (23 rows) but this time the Filter is pushed below the join!  The optimizer chooses nested loops for the join, because the cardinality estimate for rows passing the Filter is a bit low (estimate 1 versus 23 actual), though you can force a merge join with a hint and the Filter still appears below the join.  In yet another variation, the < 10 predicate can be ‘manually pushed’ by specifying it in a HAVING clause in the “q1” sub-query instead of in the WHERE clause as written above. The reason this predicate can be pushed past the join in this query form, but not in the original formulation is simply an optimizer limitation – it does make efforts (primarily during the simplification phase) to encourage logically-equivalent query specifications to produce the same execution plan, but the implementation is not completely comprehensive. Moving on to a second example, the following query specification results from phrasing the requirement as “list the products where there exists fewer than ten correlated rows in the history table”: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) < 10 ); Unfortunately, this query produces an incorrect result (86 rows): The problem is that it lists products with no history rows, though the reasons are interesting.  The COUNT_BIG(*) in the EXISTS clause is a scalar aggregate (meaning there is no GROUP BY clause) and scalar aggregates always produce a value, even when the input is an empty set.  In the case of the COUNT aggregate, the result of aggregating the empty set is zero (the other standard aggregates produce a NULL).  To make the point really clear, let’s look at product 709, which happens to be one for which no history rows exist: -- Scalar aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709;   -- Vector aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709 GROUP BY th.ProductID; The estimated execution plans for these two statements are almost identical: You might expect the Stream Aggregate to have a Group By for the second statement, but this is not the case.  The query includes an equality comparison to a constant value (709), so all qualified rows are guaranteed to have the same value for ProductID and the Group By is optimized away. In fact there are some minor differences between the two plans (the first is auto-parameterized and qualifies for trivial plan, whereas the second is not auto-parameterized and requires cost-based optimization), but there is nothing to indicate that one is a scalar aggregate and the other is a vector aggregate.  This is something I would like to see exposed in show plan so I suggested it on Connect.  Anyway, the results of running the two queries show the difference at runtime: The scalar aggregate (no GROUP BY) returns a result of zero, whereas the vector aggregate (with a GROUP BY clause) returns nothing at all.  Returning to our EXISTS query, we could ‘fix’ it by changing the HAVING clause to reject rows where the scalar aggregate returns zero: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) BETWEEN 1 AND 9 ); The query now returns the correct 23 rows: Unfortunately, the execution plan is less efficient now – it has an estimated cost of 0.78 compared to 0.33 for the earlier plans.  Let’s try adding a redundant GROUP BY instead of changing the HAVING clause: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY th.ProductID HAVING COUNT_BIG(*) < 10 ); Not only do we now get correct results (23 rows), this is the execution plan: I like to compare that plan to quantum physics: if you don’t find it shocking, you haven’t understood it properly :)  The simple addition of a redundant GROUP BY has resulted in the EXISTS form of the query being transformed into exactly the same optimal plan we found earlier.  What’s more, in SQL Server 2008 and later, we can replace the odd-looking GROUP BY with an explicit GROUP BY on the empty set: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ); I offer that as an alternative because some people find it more intuitive (and it perhaps has more geek value too).  Whichever way you prefer, it’s rather satisfying to note that the result of the sub-query does not exist for a particular correlated value where a vector aggregate is used (the scalar COUNT aggregate always returns a value, even if zero, so it always ‘EXISTS’ regardless which ProductID is logically being evaluated). The following query forms also produce the optimal plan and correct results, so long as a vector aggregate is used (you can probably find more equivalent query forms): WHERE Clause SELECT p.Name FROM Production.Product AS p WHERE ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) < 10; APPLY SELECT p.Name FROM Production.Product AS p CROSS APPLY ( SELECT NULL FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ) AS ca (dummy); FROM Clause SELECT q1.Name FROM ( SELECT p.Name, cnt = ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) FROM Production.Product AS p ) AS q1 WHERE q1.cnt < 10; This last example uses SUM(1) instead of COUNT and does not require a vector aggregate…you should be able to work out why :) SELECT q.Name FROM ( SELECT p.Name, cnt = ( SELECT SUM(1) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID ) FROM Production.Product AS p ) AS q WHERE q.cnt < 10; The semantics of SQL aggregates are rather odd in places.  It definitely pays to get to know the rules, and to be careful to check whether your queries are using scalar or vector aggregates.  As we have seen, query plans do not show in which ‘mode’ an aggregate is running and getting it wrong can cause poor performance, wrong results, or both. © 2012 Paul White Twitter: @SQL_Kiwi email: [email protected]

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• Generating Thermal Printer (Zebra Printer) Sized PDFs for FedEx Labels

  - by Michael Hart

  Background I own a company which does a lot of FedEx Ground shipping. We have a 3rd party fulfillment center, which stores some of our inventory and at our request ships it. Zebra/Thermal printers are the most cost effective shipping label printers available and our 3rd party fulfillment center has one. I want to generate the labels locally then e-mail the 3rd party fulfillment center a PDF of the labels which they can then print out on their printer. Problem The trouble is, I can't seem to figure out how to print these 4" x 6" labels to a PDF, as FedEx (both ship manager and fedex.com) uses javascript to detect what printer I have. Question What's a clever way to send my 3rd party fulfillment center a PDF (or equivalent) of our 4" x 6" zebra thermal printer labels so they can print them out without re-entering the data?

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• How should clients handle HTTP 401 with unknown authentication schemes?

  - by user113215

  What is the proper behavior for an HTTP client receiving a 401 Unauthorized response that specifies only unrecognized authentication schemes? My server supports Kerberos authentication using WWW-Authenticate: Negotiate. On the first request, the server sends a 401 Unauthorized response with a body containing an HTML document. The behavior that I expect is for clients that support Kerberos to perform that authentication and for other clients to simply display the HTML document (a login form). It seems that most of the "other clients" I've encountered do work this way, but a few do not. I haven't found anything that mandates any particular behavior in this situation. There's a brief mention in RFC 2617: HTTP Authentication: Basic and Digest Access Authentication, but is there anything more concrete? It is possible that a server may want to require Digest as its authentication method, even if the server does not know that the client supports it. A client is encouraged to fail gracefully if the server specifies only authentication schemes it cannot handle.

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• Squid site redirection

  - by AndyM

  I have an internal website that cannot be accessed from some machines on my network, due to the physical location, VPN ,network ranges etc. I would like to install Squid on "in between" network to forward request from the clients that cannot reach the website. The issue is the clients have no ability to connect to www.example.com , but they can reach a network with a squid proxy , which in turn can reach www.example.com What is the correct term I need to research in squid , is it just caching www.example.com or do I need to set the clients to use a URL that gets rewritten ? i.e www.squid-example.com -- www.example.com

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• Cannot ping my domain-joined server - Can only ping domain controller - host unreachable

  - by Vazgen

  I have a HyperV Server hosting a Domain Controller VM (192.168.1.50) and another VM (192.168.1.51) joined to this domain. I have: domain controller as DNS server forward lookup zone for the domain with host record for 192.168.1.50 and 192.168.1.51 Windows client has primary DNS server set to 192.168.1.50 and secondary to my ISP I can ping 192.168.1.50 (domain controller) successfully but cannot ping 192.168.1.51 (domain-joined VM) When pinging from Windows client: ping 192.168.1.51 Reply from 192.168.1.129 : Destination host unreachable When pinging from Domain Controller: ping 192.168.1.51 Reply from 192.168.1.50 : Destination host unreachable I have 2 virtual network adapters one PRIVATE for intranet (set to static IP 192.168.1.51) and one PUBLIC for internet with a dynamic IP. I noticed the the PUBLIC one inherited the "mydomain.com" domain subtitle after joining the domain... I don't know what this meant but it seemed more intuitive to me to switch THIS ONE to have the static IP. After I configured that I still could not ping but now I get: ping 192.168.1.51 Request timed out What seems to be the issue, I'm relatively new to networking.

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• Introducing the Oracle Parcel Service&ndash;Example/Reference Application

  - by Jeffrey West

  Over the last few weeks the product management team has been working on a webcast series that is airing in EMEA.  It is a 5-episode series where we talk about different features of WebLogic and show how to build applications that take advantage of these features.  Each session is focused at a different layer of the technology stack, and you can find the schedule below. The application we are building in this series is named the ‘Oracle Parcel Service’.  It is an example application and not a product of Oracle by any stretch of the imagination.  Over the next few weeks we will be finalizing the code and will be releasing it for you to check out.  For updates, request membership to the Oracle Parcel Service project on SampleCode.oracle.com: https://www.samplecode.oracle.com/sf/projects/oracle-parcel-svc/. Here are some of the key features that we are highlighting: JPA 2.0 (new in WebLogic 10.3.4) with EclipseLink Coherence TopLink Grid Level 2 cache for JPA JAX-RS (new in WebLogic 10.3.4) 1.0 for RESTful services Lightweight JQuery Web UI for consuming RESTful services JSF 2.0 (new in WebLogic 10.3.4) utilizing PrimeFaces EJB 3.0 Spring-WS Web Services JAX-WS Web Services Spring MDP’s for Event Driven Architectures Java MDB’s for Event Driven Architectures Partitioned Distributed Topics for Event Driven Architectures   Accessing the Code on SampleCode.Oracle.com You will need to log in using your Oracle.com username and password.  If you have not created an account, you will need to do so.  It’s a simple one-page form and we don’t bother you with too many emails.   Please join the project to be kept up to date on changes to the code and new projects.  Joining the project is not required, but very much appreciated. Once you have signed in you should see an icon for accessing the Source Code via Subversion.  You can also download a zip file containing the code.

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• Exchange Server 2007 Setup

  - by AlamedaDad

  Hi, I'm working on a upgrade to Exchange 2007 and I wanted to get some advise on hardware choices. We currently have an Exchange 2003 STD server with 400 users split between 6 AD Sites, that is housed on a single server. We need to move to a redundant, fault tolerant system to support our users. I'm planning on installing 2 Dell 1950 servers with W2k8-std to act as CAS and Hub servers, with NLB to allow abstraction of the actual server name to the users. There won't be an edge system since we have a Barracuda box already that will handle in/out spam/virus filtering. Backend I'm planning on 2 mailbox servers which will be Dell 2950s with 16GB RAM, 2 either dual-core or quad-core CPUs and 6 300GB SAS drives in some RAID config. These systems will be clustered using W2k8 Ent clustering and running CCR in Exchange. My questions are as follows: Is 16GB enough RAM for serving that many mailboxes along with the windows clustering and ccr? I'm trying to figure out disk layouts and I'm unsure of whether to use all local disk or some local and some SAN, via an OpenFiler iSCSI server. The SAN would be a Dell 2850 with 6 - 300GB SCSI drives and a PERC controller to slice as I want, with 8GB RAM. Option 1: 2 drives, RAID 1 - OS 2 drives, RAID 1 - Logs 2 drives, RAID 1 - Mail stores Option 2: 2 drives, RAID 1 - OS and logs 4 drives, RAID 5 - Mail Stores and scratch space for eseutil. Option 3: 2 drives, RAID 1 - OS 2 drives, RAID 1 - Logs 2 drives, RAID 0 - scratch space ~300GB iSCSI volume for mail stores Option 4: 2 drives, RAID 1 - OS 4 drives, RAID 5 - scratch space ~300GB iSCSI volume for mail stores ~300GB iSCSI volume for logs I have 2 sockets for CPUs and need to chose between dual and quad cores. The dual core have faster clocks but less cache and I'm thinking older architecture. Am I better off with more cores and cache while sacraficing clock speed? I am planning on adding the new E2K7 cluster to the E2K3 server and then move each mailbox over, all at once, then remove the old server. This seems more complicated than simply getting rid of the 2003 server and then adding the 2007 cluster and restoring the mailboxes using PowerControls or exmerge. The migration option lets me do this on my time, where a cutover means it all needs to work at once. If I go with the cutover method, how can I prebuild the servers and add them to the domain right after removing the 2003 server, or can't I? I think the answer is no and the migration is my only real option if I want to prebuild. I need to also migrate about 30GB of Public Folders. Is there anything special about this, other than specifying in the E2K7 install that I want older Outlook clients and PF's setup? I guess I could even keep the E2K3 server to host just the PFs? Lastly, if I have a mix of Outlook 200, 2003 and 2007 what do I need to do to make sure they all have access to the GAL and OAB? At time of cutover, we'll be at like 90% 2007, but we will have some older stuff around. My plan is to use Outlook Anywhere on laptops that are used outside the physical network. Are there any gotchas involved in that? I'm even thinking about using is for all Outlook clients, does anyone do that? The reason I'm considering it is that our WAN is really VPN tunnels over internet connections, so not a fully messhed, stable WAN. Thank you all very much for the assistance in advance and I look forward to discussion of these points! Regards...Michael

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• UI message passing programming paradigm

  - by Ronald Wildenberg

  I recently (about two months ago) read an article that explained some user interface paradigm that I can't remember the name of and I also can't find the article anymore. The paradigm allows for decoupling the user interface and backend through message passing (via some queueing implementation). So each user action results in a message being pased to the backend. The user interface is then updated to inform the user that his request is being processed. The assumption is that a user interface is stale by definition. When you read data from some store into memory, it is stale because another transaction may be updating the same data already. If you assume this, it makes no sense to try to represent the 'current' database state in the user interface (so the delay introduced by passing messages to a backend doesn't matter). If I remember correctly, the article also mentioned a read-optimized data store for rendering the user interface. The article assumed a high-traffic web application. A primary reason for using a message queue communicating with the backend is performance: returning control to the user as soon as possible. Updating backend stores is handled by another process and eventually these changes also become visible to the user. I hope I have explained accurately enough what I'm looking for. If someone can provide some pointers to what I'm looking for, thanks very much in advance.

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• Apache proxying to Unicorn server times out, how to avoid?

  - by Ian

  I have a Teambox installation running on Unicorn, and the latter sometimes times out after 30 seconds. The idea of this configuration would be for Apache to wait until the Unicorn master server sends a timeout, because if I'm not wrong, Unicorn will quit the timed-out worker process but spawn a new one to handle the same request. Is there a way to configure Apache to not timeout like the nginx configuration of timeout = 0? Thanks for the help! EDIT I found a way, though it doesn't really work as I expected. In the ProxyPass directive you have to specify a retry=0 option after the url: ProxyPass / http://url/ retry=0 It doesn't work if the url is a ProxyBalancer though.

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• Ubuntu eats itself after I followed updater instruction

  - by Tony Martin

  Updater (I assume) put a no entry style alert icon on the panel which informed me that certain package dependencies were not up to snuff. Upgrades were thereafter only partial. The dialogue advised that I (and this is from noob memory) sudo apt-get install -f. I did this and typed in the confirmation phrase and watched apt-get systematically remove every component of linux, both the stuff I installed and the core ubuntu packages. I could only assume at this stage that this was for a fresh install but of course, I know better now. There's much complaint about Windows, but I've never met with advice from Microsoft tools to wipe out the operating system because of a couple of missing .dlls. So what gives? This was a 64 bit install of 12.04. All that is left is grub pointing to a couple of windows recovery partitions on the hard drive. I'm tempted, but I have hopes of recovering the data that I had enough misguided faith to trust to the linux ext4 partition. I've tried pen driving back into it with a 32 bit iso but I'm simply informed that ubuntu is running in low graphics mode and get to watch the dots cycle indefinitely. EDIT: Thanks for the advice vis positive request. I've got onto the machine with a 64 bit stick and can see the file structure left behind by the installation. My first instinct was to run install from the stick but it did not seem to offer a recovery option. My question then: is there a way to recover the current installation so that if I reinstall the packages I had they will pick up the original settings. I'm particularly worried about losing email from evolution - the rest I could probably lash back together. I would also be interested how this disaster came about. I see people in the know recommending this same procedure in similar circumstances. Thanks for your attention, Tony Martin

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• Duplicity not writing to a pre-existing S3 bucket

  - by Saurabh Nanda

  I'm trying to backup a directory to a pre-existing Amazon S3 bucket using the following command: duplicity --no-encryption system/ s3+http://MY_BUCKET_NAME/backup However, I'm getting the following error consistently: S3CreateError: S3CreateError: 409 Conflict <?xml version="1.0" encoding="UTF-8"?> <Error><Code>BucketAlreadyOwnedByYou</Code><Message>Your previous request to create the named bucket succeeded and you already own it.</Message><BucketName>vacationlabs</BucketName><RequestId>3C1B8C49469E3374</RequestId><HostId>4dU1TKf3Td6R0yvG9MaLKCYvQfwaCpdM8FUcv53aIOh0LeJ6wtVHHduPSTqjDwt0</HostId></Error> The S3 bucket is empty and does NOT have the backup directory The bucket is in Singapore region

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• Of C# Iterators and Performance

  - by James Michael Hare

  Some of you reading this will be wondering, "what is an iterator" and think I'm locked in the world of C++.  Nope, I'm talking C# iterators.  No, not enumerators, iterators.   So, for those of you who do not know what iterators are in C#, I will explain it in summary, and for those of you who know what iterators are but are curious of the performance impacts, I will explore that as well.   Iterators have been around for a bit now, and there are still a bunch of people who don't know what they are or what they do.  I don't know how many times at work I've had a code review on my code and have someone ask me, "what's that yield word do?"   Basically, this post came to me as I was writing some extension methods to extend IEnumerable<T> -- I'll post some of the fun ones in a later post.  Since I was filtering the resulting list down, I was using the standard C# iterator concept; but that got me wondering: what are the performance implications of using an iterator versus returning a new enumeration?   So, to begin, let's look at a couple of methods.  This is a new (albeit contrived) method called Every(...).  The goal of this method is to access and enumeration and return every nth item in the enumeration (including the first).  So Every(2) would return items 0, 2, 4, 6, etc.   Now, if you wanted to write this in the traditional way, you may come up with something like this:       public static IEnumerable<T> Every<T>(this IEnumerable<T> list, int interval)     {         List<T> newList = new List<T>();         int count = 0;           foreach (var i in list)         {             if ((count++ % interval) == 0)             {                 newList.Add(i);             }         }           return newList;     }     So basically this method takes any IEnumerable<T> and returns a new IEnumerable<T> that contains every nth item.  Pretty straight forward.   The problem?  Well, Every<T>(...) will construct a list containing every nth item whether or not you care.  What happens if you were searching this result for a certain item and find that item after five tries?  You would have generated the rest of the list for nothing.   Enter iterators.  This C# construct uses the yield keyword to effectively defer evaluation of the next item until it is asked for.  This can be very handy if the evaluation itself is expensive or if there's a fair chance you'll never want to fully evaluate a list.   We see this all the time in Linq, where many expressions are chained together to do complex processing on a list.  This would be very expensive if each of these expressions evaluated their entire possible result set on call.    Let's look at the same example function, this time using an iterator:       public static IEnumerable<T> Every<T>(this IEnumerable<T> list, int interval)     {         int count = 0;         foreach (var i in list)         {             if ((count++ % interval) == 0)             {                 yield return i;             }         }     }   Notice it does not create a new return value explicitly, the only evidence of a return is the "yield return" statement.  What this means is that when an item is requested from the enumeration, it will enter this method and evaluate until it either hits a yield return (in which case that item is returned) or until it exits the method or hits a yield break (in which case the iteration ends.   Behind the scenes, this is all done with a class that the CLR creates behind the scenes that keeps track of the state of the iteration, so that every time the next item is asked for, it finds that item and then updates the current position so it knows where to start at next time.   It doesn't seem like a big deal, does it?  But keep in mind the key point here: it only returns items as they are requested. Thus if there's a good chance you will only process a portion of the return list and/or if the evaluation of each item is expensive, an iterator may be of benefit.   This is especially true if you intend your methods to be chainable similar to the way Linq methods can be chained.    For example, perhaps you have a List<int> and you want to take every tenth one until you find one greater than 10.  We could write that as:       List<int> someList = new List<int>();         // fill list here         someList.Every(10).TakeWhile(i => i <= 10);     Now is the difference more apparent?  If we use the first form of Every that makes a copy of the list.  It's going to copy the entire list whether we will need those items or not, that can be costly!    With the iterator version, however, it will only take items from the list until it finds one that is > 10, at which point no further items in the list are evaluated.   So, sounds neat eh?  But what's the cost is what you're probably wondering.  So I ran some tests using the two forms of Every above on lists varying from 5 to 500,000 integers and tried various things.    Now, iteration isn't free.  If you are more likely than not to iterate the entire collection every time, iterator has some very slight overhead:   Copy vs Iterator on 100% of Collection (10,000 iterations) Collection Size Num Iterated Type Total ms 5 5 Copy 5 5 5 Iterator 5 50 50 Copy 28 50 50 Iterator 27 500 500 Copy 227 500 500 Iterator 247 5000 5000 Copy 2266 5000 5000 Iterator 2444 50,000 50,000 Copy 24,443 50,000 50,000 Iterator 24,719 500,000 500,000 Copy 250,024 500,000 500,000 Iterator 251,521   Notice that when iterating over the entire produced list, the times for the iterator are a little better for smaller lists, then getting just a slight bit worse for larger lists.  In reality, given the number of items and iterations, the result is near negligible, but just to show that iterators come at a price.  However, it should also be noted that the form of Every that returns a copy will have a left-over collection to garbage collect.   However, if we only partially evaluate less and less through the list, the savings start to show and make it well worth the overhead.  Let's look at what happens if you stop looking after 80% of the list:   Copy vs Iterator on 80% of Collection (10,000 iterations) Collection Size Num Iterated Type Total ms 5 4 Copy 5 5 4 Iterator 5 50 40 Copy 27 50 40 Iterator 23 500 400 Copy 215 500 400 Iterator 200 5000 4000 Copy 2099 5000 4000 Iterator 1962 50,000 40,000 Copy 22,385 50,000 40,000 Iterator 19,599 500,000 400,000 Copy 236,427 500,000 400,000 Iterator 196,010       Notice that the iterator form is now operating quite a bit faster.  But the savings really add up if you stop on average at 50% (which most searches would typically do):     Copy vs Iterator on 50% of Collection (10,000 iterations) Collection Size Num Iterated Type Total ms 5 2 Copy 5 5 2 Iterator 4 50 25 Copy 25 50 25 Iterator 16 500 250 Copy 188 500 250 Iterator 126 5000 2500 Copy 1854 5000 2500 Iterator 1226 50,000 25,000 Copy 19,839 50,000 25,000 Iterator 12,233 500,000 250,000 Copy 208,667 500,000 250,000 Iterator 122,336   Now we see that if we only expect to go on average 50% into the results, we tend to shave off around 40% of the time.  And this is only for one level deep.  If we are using this in a chain of query expressions it only adds to the savings.   So my recommendation?  If you have a resonable expectation that someone may only want to partially consume your enumerable result, I would always tend to favor an iterator.  The cost if they iterate the whole thing does not add much at all -- and if they consume only partially, you reap some really good performance gains.   Next time I'll discuss some of my favorite extensions I've created to make development life a little easier and maintainability a little better.

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• Boot from VHD with windows7 - bcdedit trouble

  - by Michiel Overeem

  I'm running Windows7 Enterprise, x64 version. I've created a windows7 vhd file with help of the following blog post hanselman blog After that, I've added it to my boot menu with help of another blog post hanselman blog This worked great. After that, i've upgraded my hdd. With help of clonezilla i've copied the old disk to the new disk. Next step was to copy the vhd to another partition. Then i updated the boot menu. However, the step C:\>bcdedit /set {guid} device vhd=[driveletter:]\<directory>\<vhd filename> fails with the message An error has occurred setting the element data. The request is not supported. what is happening?

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• IIS 7 URL rewrite rule

  - by Andrew

  Hello, guys! We have here to web servers behind a router - one IIS and one Tomcat (on different machines / IP addresses). The domain is pointing to out external IP, which is forwarded to IIS (internal IP 192.168.1.10 for example). I'm trying to do the following: when [www.]ourdomain.com is entered the default web site on IIS have to be loaded (this part is ok), but when test.ourdomain.com is entered I want to redirect this request to another web server (192.168.1.11 for example). I created a site "test" on IIS and it is displayed when test.ourdomain.com is entered. Then I tried to redirect it with following rule: Requested URL matches the pattern: * (using wildcards) Condition: {HTTP_HOST} matches test.ourdomain.com Action type: Rewrite Rewrite URL: http://192.168.1.11/{R:0} but when I try to load test.ourdomain.com now I get IIS's error 404 page. Obviously I'm wrong :-) How can I do such a redirect?

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• Take Control of Workflow with Workflow Analyzer!

  - by user793553

  Take Control of Workflow with Workflow Analyzer! Immediate Analysis and Output of your EBS Workflow Environment The EBS Workflow Analyzer is a script that reviews the current Workflow Footprint, analyzes the configurations, environment, providing feedback, and recommendations on Best Practices and areas of concern. Go to Doc ID 1369938.1  for more details and script download with a short overview video on it. Proactive Benefits: Immediate Analysis and Output of Workflow Environment Identifies Aged Records Identifies Workflow Errors & Volumes Identifies looping Workflow items and stuck activities Identifies Workflow System Setup and configurations Identifies and Recommends Workflow Best Practices Easy To Add Tool for regular Workflow Maintenance Execute Analysis anytime to compare trending from past outputs The Workflow Analyzer presents key details in an easy to review graphical manner.   See the examples below. Workflow Runtime Data Table Gauge The Workflow Runtime Data Table Gauge will show critical (red), bad (yellow) and good (green) depending on the number of workflow items (WF_ITEMS).   Workflow Error Notifications Pie Chart A pie chart shows the workflow error notification types.   Workflow Runtime Table Footprint Bar Chart A pie chart shows the workflow error notification types and a bar chart shows the workflow runtime table footprint.   The analyzer also gives detailed listings of setups and configurations. As an example the workflow services are listed along with their status for review:   The analyzer draws attention to key details with yellow and red boxes highlighting areas of review:   You can extend on any query by reviewing the SQL Script and then running it on your own or making modifications for your own needs:     Find more details in these notes: Doc ID 1369938.1 Workflow Analyzer script for E-Business Suite Worklfow Monitoring and Maintenance Doc ID 1425053.1 How to run EBS Workflow Analyzer Tool as a Concurrent Request Or visit the My Oracle Support EBS - Core Workflow Community  

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• Should I include HTML markup in my JSON response?

  - by Mike M. Lin

  In an e-commerce site, when adding an item to a cart, I'd like to show a popup window with the options you can choose. Imagine you're ordering an iPod Shuffle and now you have to choose the color and text to engrave. I'd like the window to be modal, so I'm using a lightbox populated by an Ajax call. Now I have two options: Option 1: Send only the data, and generate the HTML markup using JavaScript What's nice about this is that it trims down the Ajax request to the bear minimum and doesn't mix the data with the markup. What's not so great about this is that now I need to use JavaScript to do my rendering, instead of having a template engine on the server-side do it. I might be able to clean up the approach a bit by using a client-side templating solution. Option 2: Send the HTML markup What's good about this is that I can have the same server-side templating engine I'm using for the rest of my rendering tasks (Django), do the rendering of the lightbox. JavaScript is only used to insert the HTML fragment into the page. So it clearly leaves the rendering to the rendering engine. Makes sense to me. But I don't feel comfortable mixing data and markup in an Ajax call for some reason. I'm not sure what makes me feel uneasy about it. I mean, it's the same way every web page is served up -- data plus markup -- right?

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• How to resolve IPs in DNS based on the subnet of the requesting client?

  - by Nohsib

  Is it possible to configure Bind9 or other DNS to resolve the domain name of a machine into different IPs based on the subnet of the requesting client? e.g. Say the same service is running on 2 different application servers at different geographical points and based on the incoming request to resolve the domain name, the name server provides the IP of the application server based on the requesting client's IP, so the service could be offered by servers that are geographically closer to the client. In short, something like a CDN but just the IP resolution part based on the client's subnet. Is this configurable in any DNS?

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• Understanding HTTP Cookies in Indy 10 for Delphi XE2

  - by Jerry Dodge

  I have been working with Indy 10 HTTP Servers / Clients lately in Delphi XE2, and I need to make sure I'm understanding session management correctly. In the server, I have a "bucket" of sessions, which is a list of objects which each represent a unique session. I don't use username and password to authenticate users, but I rather use a unique API key which is issued to a client, and has an expiration. When a client wishes to connect to the server, it first logs in by calling the "login" command, which is a path like this: http://localhost:1234/login?APIKey=abcdefghij. The server checks this API Key against the database, and if it's valid, it creates a new session in the bucket, issues a new cookie (unique string), and sets the response cookies with Success=Y and Cookie=abcdefghij. This is where I have the question. Assuming the client end has its own method of cookie management, the client will receive this login response back from the server and automatically save the cookies as necessary. Any future request from the client to the server shall automatically send along these cookies, and the client side doesn't have to necessarily worry about setting these cookies when sending requests to the server. Right? PS - I'm asking this question here on programmers.stackexchange.com because I didn't see it fit to ask on stackoverflow.com. If anyone thinks this is appropriate enough for stackoverflow.com, please let me know.

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• Forwarding a subdomain to main domain using Godaddy.

  - by Ryan Hayes

  I have current blog, which was hosted on Tumblr at http://blog.ryanhayes.net. I'm moving it over to http://ryanhayes.net, and have all the 301 redirects set up for the blog entries to map to my new blog, which is hosted using Godaddy (domain included). When I try to set up a subdomain forward, I'm greeted with a nice 403 Forbidden response (as of this writing, you can see it at http://blog.ryanhayes.net. When I try to ping both the subdomain and domain, they point to the same IP address, so I know blog subdomain has at least switched over to point to the same content. I don't really understand why I would get a 403 Forbidden on the same content that I can see perfectly fine via another domain. Currently, I have a CNAME of blog pointing to @, which is how "www" is set up to forward, so I'm assuming it would do the same thing. My question is what is the proper way to set up my DNS to make the blog subdomain forward to my main domain (301) using the GoDaddy DNS manager? Bonus: What is the background on why I am getting a 403 error the current way? Forbidden You don't have permission to access / on this server. Additionally, a 403 Forbidden error was encountered while trying to use an ErrorDocument to handle the request. UPDATE 12/7/2010 Error on site has been fixed, you can no longer view it from my site.

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• Cannot read/access Apache2 access logs

  - by webworm

  I have been asked to take a look at some access logs for an Apcahe2 web server running on Ubuntu. I have been told by the administrator of the machine that my login has "admin" access yet I cannot seem to copy the access logs from Apache2 to my local machine via FTP for analysis. I figure one of two things is happening ... I don't really have full admin access Some other process (perhaps Apache2) has control of the log files and won't let me copy them. How can I tell if I truly have admin access? What type of access do I need to request? Root access? Something else? Should I be able to copy these log files with admin access?

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• Internet cafe software for linux

  - by pehrs

  I have gotten a request to roll out a total of 8 internet cafe's in a large network. Budget is non-existent as it will all be done for a non-profit. I was planing to use Ubuntu and live-cds to minimize the amount of management required, but I can't seem to find any suitable internet cafe system that is Ubuntu based. The requirements are pretty basic: It needs to keep track of logged in time and log out users when their time it up. No billing will be done, it will just be used to ensure people can share the computers fairly. It should be possible to force logout from a central system. Users will be unskilled, so it has to have a GUI. What (preferably free, considering the shoe-string budget) software would you suggest to manage this?

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• dhcpd: varying vendor-class-identifier

  - by jessicah

  I'm having trouble selectively sending parameters in response to a DHCP Inform packet using groups (or even without, just using host declarations) for bootp stuff. My configuration file right now looks like: subnet 130.123.131.128 netmask 255.255.255.128 { allow unknown-clients; } host dev-mac-09 { option vendor-class-identifier "example-identifier"; hardware ethernet 10:9a:dd:51:ff:83; } If I put vendor-class-identifier in the global scope, using tcpdump I can see that the client receives the vendor class option successfully. If I take it out, and just keep it in the host scope (or group scope), the client never receives the option. Specifying option dhcp-parameter-request list 60 doesn't help either. I did try using a class definition inside a group, but then it applied even if the host wasn't a part of the group. As an aside, how do I get detailed logging? At least something to indicate what groups and things got used to generate the response to the client.

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• Issues importing PST into Archive Mailbox Exchange 2013

  - by atomicharri

  I've completed a successful mailbox import request into the archive mailbox for a particular user. There are no errors to speak of and the size of the archive mailbox has grown to the expected size after import (approximately 6GB). However, in OWA I can't see any of the mail folders inside the archive mailbox, only Deleted Items and RSS feeds folders. However if I run some cmdlets to list the contents of the Archive Mailbox\Inbox folder in the Exchange Shell, the full list of subfolders will come up. If I do a mail item search on the archive mailbox, emails from those individual folders appear as search results! I just can't see the folders in the navigation pane and hence cannot browse any of my old emails. Any help would be appreciated.

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