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  • Unable to install Ubuntu 12.10 on windows 8 machine/ error no5

    - by JOBIN VARGHESE
    installing crashes at halfway of 'copying files' showing an i\o device error error no5; there was problem in beginning of installation too, ubuntu was not detecting the installed windows 8. my system is a dell inspiron 5520 laptop ,with 1 tb WDC hard disk in GPT ,with EFI . my current partition is like 102 mb EFI SYSTEM partition 200 gb Windows 8 ntfs 22 gb root Ext4 8 gb swap 20 db home Ext4 680 gb ntfs Drive for storing all my files. i tried both dvd disc and usb drive, both resulted in same error. inbuild dell hardware diagnosis utility showed both hard disk and dvd drive as healthy what may be the reason and how can i install ubuntu along side my windows 8?

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  • Développement d'applications professionnelles avec Android 2 de Reto Meier, critique par verdvaine yan

    Je viens de lire "Développement d'applications professionnelles avec Android 2" de Reto Meier, ingénieur chez Google. [IMG]http://images-eu.amazon.com/images/P/274402452X.08.LZZZZZZZ.jpg[/IMG] Je le trouve très complémentaire aux tutoriaux qu'on trouve sur Internet. Il aborde beaucoup de sujets et le nombre de pages n'est pas dù à des captures d'écrans ! Ce que j'ai particulièremen apprécié, ce sont toutes les petites informations tirées de son expérience qu'il distille au fil des pages. L'avez vous lu ? Si oui, par rapport à d'autres livres sur le sujet ? Allez vous le lire ?...

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  • monotouch 2d pixel with correct resolution

    - by acidzombie24
    I am writing up a game that is size sensitive. It needs to be pixel perfect. I believe the resolution is 480x320 pixels with the iphone being twice the width and height. My code is grid based with images exactly 16x16pixels. I found samples of opengl in the past but I never found any good tutorial that had 0,0 the top left and was the correct size in resolution (which made images look terrible) What can I use? I'd like to write the code in C# (or C++ but C# is preferred) and use monotouch. I don't know any libraries for 2d graphics. I'll figure out sound and such afterwards and I seen documentation on monotouch for input.

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  • Solving Big Problems with Oracle R Enterprise, Part II

    - by dbayard
    Part II – Solving Big Problems with Oracle R Enterprise In the first post in this series (see https://blogs.oracle.com/R/entry/solving_big_problems_with_oracle), we showed how you can use R to perform historical rate of return calculations against investment data sourced from a spreadsheet.  We demonstrated the calculations against sample data for a small set of accounts.  While this worked fine, in the real-world the problem is much bigger because the amount of data is much bigger.  So much bigger that our approach in the previous post won’t scale to meet the real-world needs. From our previous post, here are the challenges we need to conquer: The actual data that needs to be used lives in a database, not in a spreadsheet The actual data is much, much bigger- too big to fit into the normal R memory space and too big to want to move across the network The overall process needs to run fast- much faster than a single processor The actual data needs to be kept secured- another reason to not want to move it from the database and across the network And the process of calculating the IRR needs to be integrated together with other database ETL activities, so that IRR’s can be calculated as part of the data warehouse refresh processes In this post, we will show how we moved from sample data environment to working with full-scale data.  This post is based on actual work we did for a financial services customer during a recent proof-of-concept. Getting started with the Database At this point, we have some sample data and our IRR function.  We were at a similar point in our customer proof-of-concept exercise- we had sample data but we did not have the full customer data yet.  So our database was empty.  But, this was easily rectified by leveraging the transparency features of Oracle R Enterprise (see https://blogs.oracle.com/R/entry/analyzing_big_data_using_the).  The following code shows how we took our sample data SimpleMWRRData and easily turned it into a new Oracle database table called IRR_DATA via ore.create().  The code also shows how we can access the database table IRR_DATA as if it was a normal R data.frame named IRR_DATA. If we go to sql*plus, we can also check out our new IRR_DATA table: At this point, we now have our sample data loaded in the database as a normal Oracle table called IRR_DATA.  So, we now proceeded to test our R function working with database data. As our first test, we retrieved the data from a single account from the IRR_DATA table, pull it into local R memory, then call our IRR function.  This worked.  No SQL coding required! Going from Crawling to Walking Now that we have shown using our R code with database-resident data for a single account, we wanted to experiment with doing this for multiple accounts.  In other words, we wanted to implement the split-apply-combine technique we discussed in our first post in this series.  Fortunately, Oracle R Enterprise provides a very scalable way to do this with a function called ore.groupApply().  You can read more about ore.groupApply() here: https://blogs.oracle.com/R/entry/analyzing_big_data_using_the1 Here is an example of how we ask ORE to take our IRR_DATA table in the database, split it by the ACCOUNT column, apply a function that calls our SimpleMWRR() calculation, and then combine the results. (If you are following along at home, be sure to have installed our myIRR package on your database server via  “R CMD INSTALL myIRR”). The interesting thing about ore.groupApply is that the calculation is not actually performed in my desktop R environment from which I am running.  What actually happens is that ore.groupApply uses the Oracle database to perform the work.  And the Oracle database is what actually splits the IRR_DATA table by ACCOUNT.  Then the Oracle database takes the data for each account and sends it to an embedded R engine running on the database server to apply our R function.  Then the Oracle database combines all the individual results from the calls to the R function. This is significant because now the embedded R engine only needs to deal with the data for a single account at a time.  Regardless of whether we have 20 accounts or 1 million accounts or more, the R engine that performs the calculation does not care.  Given that normal R has a finite amount of memory to hold data, the ore.groupApply approach overcomes the R memory scalability problem since we only need to fit the data from a single account in R memory (not all of the data for all of the accounts). Additionally, the IRR_DATA does not need to be sent from the database to my desktop R program.  Even though I am invoking ore.groupApply from my desktop R program, because the actual SimpleMWRR calculation is run by the embedded R engine on the database server, the IRR_DATA does not need to leave the database server- this is both a performance benefit because network transmission of large amounts of data take time and a security benefit because it is harder to protect private data once you start shipping around your intranet. Another benefit, which we will discuss in a few paragraphs, is the ability to leverage Oracle database parallelism to run these calculations for dozens of accounts at once. From Walking to Running ore.groupApply is rather nice, but it still has the drawback that I run this from a desktop R instance.  This is not ideal for integrating into typical operational processes like nightly data warehouse refreshes or monthly statement generation.  But, this is not an issue for ORE.  Oracle R Enterprise lets us run this from the database using regular SQL, which is easily integrated into standard operations.  That is extremely exciting and the way we actually did these calculations in the customer proof. As part of Oracle R Enterprise, it provides a SQL equivalent to ore.groupApply which it refers to as “rqGroupEval”.  To use rqGroupEval via SQL, there is a bit of simple setup needed.  Basically, the Oracle Database needs to know the structure of the input table and the grouping column, which we are able to define using the database’s pipeline table function mechanisms. Here is the setup script: At this point, our initial setup of rqGroupEval is done for the IRR_DATA table.  The next step is to define our R function to the database.  We do that via a call to ORE’s rqScriptCreate. Now we can test it.  The SQL you use to run rqGroupEval uses the Oracle database pipeline table function syntax.  The first argument to irr_dataGroupEval is a cursor defining our input.  You can add additional where clauses and subqueries to this cursor as appropriate.  The second argument is any additional inputs to the R function.  The third argument is the text of a dummy select statement.  The dummy select statement is used by the database to identify the columns and datatypes to expect the R function to return.  The fourth argument is the column of the input table to split/group by.  The final argument is the name of the R function as you defined it when you called rqScriptCreate(). The Real-World Results In our real customer proof-of-concept, we had more sophisticated calculation requirements than shown in this simplified blog example.  For instance, we had to perform the rate of return calculations for 5 separate time periods, so the R code was enhanced to do so.  In addition, some accounts needed a time-weighted rate of return to be calculated, so we extended our approach and added an R function to do that.  And finally, there were also a few more real-world data irregularities that we needed to account for, so we added logic to our R functions to deal with those exceptions.  For the full-scale customer test, we loaded the customer data onto a Half-Rack Exadata X2-2 Database Machine.  As our half-rack had 48 physical cores (and 96 threads if you consider hyperthreading), we wanted to take advantage of that CPU horsepower to speed up our calculations.  To do so with ORE, it is as simple as leveraging the Oracle Database Parallel Query features.  Let’s look at the SQL used in the customer proof: Notice that we use a parallel hint on the cursor that is the input to our rqGroupEval function.  That is all we need to do to enable Oracle to use parallel R engines. Here are a few screenshots of what this SQL looked like in the Real-Time SQL Monitor when we ran this during the proof of concept (hint: you might need to right-click on these images to be able to view the images full-screen to see the entire image): From the above, you can notice a few things (numbers 1 thru 5 below correspond with highlighted numbers on the images above.  You may need to right click on the above images and view the images full-screen to see the entire image): The SQL completed in 110 seconds (1.8minutes) We calculated rate of returns for 5 time periods for each of 911k accounts (the number of actual rows returned by the IRRSTAGEGROUPEVAL operation) We accessed 103m rows of detailed cash flow/market value data (the number of actual rows returned by the IRR_STAGE2 operation) We ran with 72 degrees of parallelism spread across 4 database servers Most of our 110seconds was spent in the “External Procedure call” event On average, we performed 8,200 executions of our R function per second (110s/911k accounts) On average, each execution was passed 110 rows of data (103m detail rows/911k accounts) On average, we did 41,000 single time period rate of return calculations per second (each of the 8,200 executions of our R function did rate of return calculations for 5 time periods) On average, we processed over 900,000 rows of database data in R per second (103m detail rows/110s) R + Oracle R Enterprise: Best of R + Best of Oracle Database This blog post series started by describing a real customer problem: how to perform a lot of calculations on a lot of data in a short period of time.  While standard R proved to be a very good fit for writing the necessary calculations, the challenge of working with a lot of data in a short period of time remained. This blog post series showed how Oracle R Enterprise enables R to be used in conjunction with the Oracle Database to overcome the data volume and performance issues (as well as simplifying the operations and security issues).  It also showed that we could calculate 5 time periods of rate of returns for almost a million individual accounts in less than 2 minutes. In a future post, we will take the same R function and show how Oracle R Connector for Hadoop can be used in the Hadoop world.  In that next post, instead of having our data in an Oracle database, our data will live in Hadoop and we will how to use the Oracle R Connector for Hadoop and other Oracle Big Data Connectors to move data between Hadoop, R, and the Oracle Database easily.

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  • CodePlex Daily Summary for Tuesday, November 30, 2010

    CodePlex Daily Summary for Tuesday, November 30, 2010Popular ReleasesSense/Net Enterprise Portal & ECMS: SenseNet 6.0.1 Community Edition: Sense/Net 6.0.1 Community Edition This half year we have been working quite fiercely to bring you the long-awaited release of Sense/Net 6.0. Download this Community Edition to see what we have been up to. These months we have worked on getting the WebCMS capabilities of Sense/Net 6.0 up to par. New features include: New, powerful page and portlet editing experience. HTML and CSS cleanup, new, powerful site skinning system. Upgraded, lightning-fast indexing and query via Lucene. Limita...Minecraft GPS: Minecraft GPS 1.1.1: New Features Compass! New style. Set opacity on main window to allow overlay of Minecraft. Open World in any folder. Fixes Fixed style so listbox won't grow the window size. Fixed open file dialog issue on non-vista kernel machines.DotSpatial: DotSpatial 11-28-2001: This release introduces some exciting improvements. Support for big raster, both in display and changing the scheme. Faster raster scheme creation for all rasters. Caching of the "sample" values so once obtained the raster symbolizer dialog loads faster. Reprojection supported for raster and image classes. Affine transform fully supported for images and rasters, so skewed images are now possible. Projection uses better checks when loading unprojected layers. GDAL raster support f...Virtu: Virtu 0.9.0: Source Requirements.NET Framework 4 Visual Studio 2010 or Visual Studio 2010 Express Silverlight 4 Tools for Visual Studio 2010 Windows Phone 7 Developer Tools (which includes XNA Game Studio 4) Binaries RequirementsSilverlight 4 .NET Framework 4 XNA Framework 4SuperWebSocket: SuperWebSocket(60438): It is the first release of SuperWebSocket. Because it is base on SuperSocket, most features of SuperSocket are supported in SuperWebSocket. The source code include a LiveChat demo.MDownloader: MDownloader-0.15.25.7002: Fixed updater Fixed FileServe Fixed LetItBitNotepad.NET: Notepad.NET 0.7 Preview 1: Whats New?* Optimized Code Generation: Which means it will run significantly faster. * Preview of Syntax Highlighting: Only VB.NET highlighting is supported, C# and Ruby will come in Preview 2. * Improved Editing Updates (when the line number, etc updates) to be more graceful. * Recent Documents works! * Images can be inserted but they're extremely large. Known Bugs* The Update Process hangs: This is a bug apparently spawning since 0.5. It will be fixed in Preview 2. Until then, perform a fr...Cropper: 1.9.4: Mostly fixes for issues with a few feature requests. Fixed Issues 2730 & 3638 & 14467 11044 11447 11448 11449 14665 Implemented Features 6123 11581PFC: PFC for PB 11.5: This is just a migration from the 11.0 code. No changes have been made yet (and they are needed) for it to work properly with 11.5.PDF Rider: PDF Rider 0.5: This release does not add any new feature for pdf manipulation, but enables automatic updates checking, so it is reccomended to install it in order to stay updated with next releases. Prerequisites * Microsoft Windows Operating Systems (XP - Vista - 7) * Microsoft .NET Framework 3.5 runtime * A PDF rendering software (i.e. Adobe Reader) that can be opened inside Internet Explorer. Installation instructionsChoose one of the following methods: 1. Download and run the "pdfRider0...BCLExtensions: BCL Extensions v1.0: The files associated with v1.0 of the BCL Extensions library.XamlQuery/WPF - The Write Less, Do More, WPF Library: XamlQuery-WPF v1.2 (Runtime, Source): This is the first release of popular XamlQuery library for WPF. XamlQuery has already gained recognition among Silverlight developers.Math.NET Numerics: Beta 1: First beta of Math.NET Numerics. Only contains the managed linear algebra provider. Beta 2 will include the native linear algebra providers along with better documentation and examples.Microsoft All-In-One Code Framework: Visual Studio 2010 Code Samples 2010-11-25: Code samples for Visual Studio 2010Wii Backup Fusion: Wii Backup Fusion 0.8.5 Beta: - WBFS repair (default) options fixed - Transfer to image fixed - Settings ui widget names fixed - Some little bug fixes You need to reset the settings! Delete WiiBaFu's config file or registry entries on windows: Linux: ~/.config/WiiBaFu/wiibafu.conf Windows: HKEY_CURRENT_USER\Software\WiiBaFu\wiibafu Mac OS X: ~/Library/Preferences/com.wiibafu.wiibafu.plist Caution: This is a BETA version! Errors, crashes and data loss not impossible! Use in test environments only, not on productive syste...Minemapper: Minemapper v0.1.3: Added process count and world size calculation progress to the status bar. Added View->'Status Bar' menu item to show/hide the status bar. Status bar is automatically shown when loading a world. Added a prompt, when loading a world, to use or clear cached images.Sexy Select: sexy select v0.4: Changes in v0.4 Added method : elements. This returns all the option elements that are currently added to the select list Added method : selectOption. This method accepts two values, the element to be modified and the selected state. (true/false)Deep Zoom for WPF: First Release: This first release of the Deep Zoom control has the same source code, binaries and demos as the CodeProject article (http://www.codeproject.com/KB/WPF/DeepZoom.aspx).BlogEngine.NET: BlogEngine.NET 2.0 RC: This is a Release Candidate version for BlogEngine.NET 2.0. The most current, stable version of BlogEngine.NET is version 1.6. Find out more about the BlogEngine.NET 2.0 RC here. If you want to extend or modify BlogEngine.NET, you should download the source code. To get started, be sure to check out our installation documentation and the installation screencast. If you are upgrading from a previous version, please take a look at the Upgrading to BlogEngine.NET 2.0 instructions. As this ...NodeXL: Network Overview, Discovery and Exploration for Excel: NodeXL Excel Template, version 1.0.1.156: The NodeXL Excel template displays a network graph using edge and vertex lists stored in an Excel 2007 or Excel 2010 workbook. What's NewThis release adds a feature for aggregating the overall metrics in a folder full of NodeXL workbooks, adds geographical coordinates to the Twitter import features, and fixes a memory-related bug. See the Complete NodeXL Release History for details. Please Note: There is a new option in the setup program to install for "Just Me" or "Everyone." Most people...New ProjectsActiveRecordTest: ActiveRecordTest is a sample project that is really a quick guide for start using Castle ActiveRecord within an ASP.NET web application.BacteriaManage: just test codeplexDS CMS: Diamond Shop - open source project. 1. ASP.NET MVC 3.0 2. Entity Framework 3. Jquery 4. LinqGeneral Media Access WebService: This project is focused on building a general purpose media access webservice based on WCF.JavaEE server for XUNU: C'est le serveur internet du site à ChoupieLearning management system: Learning management system to help teachers on their work.LogWriterReader using Named pipe: LogWriterReader using Named pipeNMix: NMix???EntLib,NHibernate,log4net??????????,????????????????,?????????、?????、????、????、?????????。Nosso Rico Dinheirinho: Financial control system like Microsoft Money, but via web.Post Template: Post Template (for now) is for craigslist posters looking to make their posts more visually appealing. Abstracting the styling and layout details of HTML and CSS, Post Template eliminates the need to know these languages when posting. Post Template is mostly written in C#.SharePoint Silverlight Clock: SharePoint Silverlight ClockSilverlight MVVM wizard using Caliburn Micro: This MVVM style Silverlight 4 wizard shows some Caliburn Micro features, as well as the use of MEF and MVVM style unit testing. The UI and code are based on the code accompanying the "Code Project" article "Creating an Internationalized Wizard in WPF" from dec. 2008.Spider Framework: A ruler-based spider framework developing with C#syx Open Source Project: syx Open Source ProjectTigerCat: TigerCat will support application development as infrastructure and RAD tools.TitleNetSolution: This my team Solution.!Uploadert: UploadertWidget Suite for DotNetNuke: This project is intended to hold a suite of useful widgets to make your skinning easier, and raise the level of interactivity with DotNetNuke website visitors.ZenBridge for Picasa: ZenBridge for Picasa makes it easy for Zenfolio users to upload edited images directly to a chosen Zenfolio gallery. It's developed in C#.NET 4.

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  • Autodetect/mount SDCards and run script for them on Linux

    - by Brendan
    Hey Everyone, I'm currently running SME Server, and need to have a script run upon the attachment of SD Cards to my server. The script itself works fine (it copies the contents of the cards), but the automounting and execution of the script is where I'm having issues. The I have a USB hub consisting of 10 USB ports; that shows up as: [root@server ~]# lsusb Bus 004 Device 002: ID 0000:0000 Bus 004 Device 001: ID 0000:0000 Bus 003 Device 001: ID 0000:0000 Bus 002 Device 001: ID 0000:0000 Bus 001 Device 055: ID 1a40:0101 TERMINUS TECHNOLOGY INC. Bus 001 Device 051: ID 1a40:0101 TERMINUS TECHNOLOGY INC. Bus 001 Device 050: ID 1a40:0101 TERMINUS TECHNOLOGY INC. Bus 001 Device 001: ID 0000:0000 (The hub is the TERMINUS TECHNOLOGY INC entries) As I cannot plug SD Cards directly into the server; I use a USB to SD card attachement (10 of them) plugged into the hub to read the cards. Upon pluggig the 10 attachments (without cards) into the hub; lsusb yields the following: [root@server ~]# lsusb Bus 004 Device 002: ID 0000:0000 Bus 004 Device 001: ID 0000:0000 Bus 003 Device 001: ID 0000:0000 Bus 002 Device 001: ID 0000:0000 Bus 001 Device 073: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 072: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 071: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 070: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 069: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 068: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 067: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 066: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 065: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 064: ID 05e3:0723 Genesys Logic, Inc. Bus 001 Device 055: ID 1a40:0101 TERMINUS TECHNOLOGY INC. Bus 001 Device 051: ID 1a40:0101 TERMINUS TECHNOLOGY INC. Bus 001 Device 050: ID 1a40:0101 TERMINUS TECHNOLOGY INC. Bus 001 Device 001: ID 0000:0000 As you can see, the readers are the "Gensys Logic, Inc" entries. Plugging in an SD card to a reader doesn't affect lsusb (it reads exactly as above), however my system recognises the cards fine; as indicated by dmesg: Attached scsi generic sg11 at scsi54, channel 0, id 0, lun 0, type 0 USB Mass Storage device found at 73 SCSI device sdd: 31388672 512-byte hdwr sectors (16071 MB) sdd: Write Protect is on sdd: Mode Sense: 03 00 80 00 sdd: assuming drive cache: write through SCSI device sdd: 31388672 512-byte hdwr sectors (16071 MB) sdd: Write Protect is on sdd: Mode Sense: 03 00 80 00 sdd: assuming drive cache: write through sdd: sdd1 SCSI device sdd: 31388672 512-byte hdwr sectors (16071 MB) sdd: Write Protect is on sdd: Mode Sense: 03 00 80 00 sdd: assuming drive cache: write through SCSI device sdd: 31388672 512-byte hdwr sectors (16071 MB) sdd: Write Protect is on sdd: Mode Sense: 03 00 80 00 sdd: assuming drive cache: write through sdd: sdd1 SCSI device sdd: 31388672 512-byte hdwr sectors (16071 MB) sdd: Write Protect is on sdd: Mode Sense: 03 00 80 00 sdd: assuming drive cache: write through SCSI device sdd: 31388672 512-byte hdwr sectors (16071 MB) sdd: Write Protect is on sdd: Mode Sense: 03 00 80 00 sdd: assuming drive cache: write through sdd: sdd1 If I manually mount sdd1 (mount /dev/sdd1 /somedirectory/) this works fine. What I'm really after is a solution that automounts each of the cards as they are inputted into the reader; and executes a script for them (this will involve copying their contents to another directory). My problem is that I don't know how to do this; I don't think udev will work as the USB devices don't change; if I could somehow get udev working with /dev/disk/by-path/ however I think this is doable (it seems to keep constant entries). ls /dev/disk returns: pci-0000:00:1d.7-usb-0:4.1.1.1:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.1.1.2:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.1.1.3:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.1.1.4:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.1.2:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.1.3:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.1.4:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.2:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.3:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.4:1.0-scsi-0:0:0:0 pci-0000:00:1d.7-usb-0:4.4:1.0-scsi-0:0:0:0-part1 pci-0000:0b:01.0-scsi-0:0:1:0 pci-0000:0b:01.0-scsi-0:0:1:0-part1 pci-0000:0b:01.0-scsi-0:0:1:0-part2 From above, we can see I have only one card plugged into the reader (pci-0000:00:1d.7-usb-0:4.4:1.0-scsi-0:0:0:0-part1). Going mount /dev/disk/by-path/pci-0000\:00\:1d.7-usb-0\:4.4\:1.0-scsi-0\:0\:0\:0-part1 Works and places the card under /media/usbdisk/, however: mount /dev/disk/by-path/pci-0000\:00\:1d.7-usb-0\:4.4\:1.0-scsi-0\:0\:0\:0-part1 slot1/ doesn't work, and returns "mount: can't get address for /dev/disk/by-path/pci-0000" Any ideas and solutions would be great, I've seen the knowledge of a lot of the guys on here before so I'm hopeful someone can help me out. Thanks

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  • How to fix 'grub error file not found' when installing 12.04?

    - by Tomasz Grabowski
    i'm trying to install Ubuntu. I don't know if it is important, but i'm trying to install it on external HDD. In the end i have external bootable HDD which only displays: error: file not found grub recovery> From the beginning: I've downloaded ubuntu-12.04-desktop-i386.iso I've used LiLi USB Creator (LinuxLive) to create bootable pendrive from that image I've bootet from it, it works I've clicked "Try ubuntu", it works too. I've used GParted to look over drivers (disks) My primary embedded disk is seen as /dev/sda My attached external disk as /dev/sdb My PenDrive as /dev/sdc I've created partitions on /dev/sdb Fist partition for system (over 200GiB) Second was there already (it's xsf, and i don't want to touch it :P) Third is extended partition, with 1 locital partiton (10GiB) for swap I've started installation i've choose "somethin else" in ... i belive secound screeb then is selected /dev/sdb as boot disk for first partiton of /dev/sdb i set i want ext3 file system, i've check "formattin" checkbox, and mount path set to "/" firs logical partiton set as swap partition After installation finished, i restarted my computer. When i boot from my primary disc it's work ok, my previous operating system - vista - works ok. When i set my BIOS to boot from my external disc, i only get that message: error: file not found grub recovery> I've try to reinstall it, but didn't help... In desperation, i've try to read a bit about that "grub recovery" command-line and experiment a bit... I'm not sure if this has had any point, or if it give you some information (notice, that i don't know what i'm doing :P ) when i've type command: insmod (hd1,1)/boot/grub/linux.mod i've get message: unknown filesystem the same with: insmod (hd1,msdos1)/boot/grub/linux.mod the same with: insmod ext3 but i get no message after command: insmod ext2 ... notice that i really don't know what this command exactly do, but than i thought that maybe if i reinstall ubuntu with ext2 filesystem, it will work. I've done that, but symptoms are the same. I've go back to that Live version of ubuntu, filesystem and basics directories seems to be present on /dev/sdb1 ... i'm completely unfamiliar with GRUB. I'm also don't know which wersion of GRUB it is, i hope there is only one version on ubuntu-12.04-desktop-i386.iso Any help? Thax

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  • Asciifi Is a Lightening Fast Web-Based ASCII Converter

    - by Jason Fitzpatrick
    If you have a hankering from some old-school ASCII artwork, Asciifi is a free and lightening fast HTML5 ASCII converter. Despite the simplicity of ASCII images (pictures created not out of a grid of colored pixels like a standard digital photograph but out of a grid of text characters) many ASCII converters are rather slow. Asciifi speeds up the process by rendering your images on the fly with a snappy HTML5-based converter. Visit the site, drag and drop your image, and almost instantaneously you’ll see the results. The output can be further tweaked by adjusting the line width and the character set used. Hit up the link below to take it for a test drive. Asciifi [via Digital Inspiration] HTG Explains: Understanding Routers, Switches, and Network Hardware How to Use Offline Files in Windows to Cache Your Networked Files Offline How to See What Web Sites Your Computer is Secretly Connecting To

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  • Grub messed up on dual boot machine - can't boot live usb

    - by Sam
    I have a laptop on which I had Win 7 and Ubuntu 12.04 installed. The hdd has two partitions (one primary and one extended). Grub wasn't loaing initially so I ran the boot disk repair tool which seemed to sort it out. However, I mistakenly removed python (long story) from the Ubuntu OS and this obviously messed up Ubuntu a lot. So I decided to reintsall both Win7 and Ubuntu 12.04 in an attempt to get things back fresh. Win 7 went fine, but now when I try and use the Live USB to install Ubuntu I get: error: no such device: grub rescue I guess grub is still there despite the Win 7 reinstall and it can't find the partition for Ubuntu (which I deleted prior to the fresh install). I have tried fixmbr in windows console and the boot-repair-disk utility, but no joy. I cannot boot the live usb so no access to linux. A real mess. Any suggestions from the community?

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  • Impossible to install Ubuntu 10.10 dual boot with Windows 7 on new Acer desktop computer

    - by Don Myers
    My brother has a brand new Acer Desktop with Windows 7. I have done many installs (40+) of Ubuntu starting with 8.10, and have never run into this. I've spent three hours trying to do a dual boot install of 10.10. When you get to the place where you normally would choose to install as a dual boot or overwrite the existing information on the hard drive, that block is just blank. Nothing. No choices even to do a manual partition setup. If you try to go on you get the message "No root file system is defined. Please correct this from the partitioning menu." but there is nothing in the partitioning menu. I tried a good 10.04 disc also. Same thing happens with it. I ran a gparted live cd, and it shows the hard drive as sda with 3 partitions on the original. sda1 is a small partition called PQService. sda2 is another small partition called System Reserved, and GParted says it is the boot partition. sda3 is the main partation with the operating system (Windows 7) and all of the empty space. There is a little unallocated space at the very beginning and very end of the hard drive. If I go to places in the Live CD, it shows a 640 gb hard disk called Acer, but it also shows a 640 gb hard disk called system reserved. They are the same disk. There is just one hard drive. If you click properties in the System Reserved 640 gb, it shows all information as unknown. I had to change the boot order in the bios in order to run the live cd. The hard drive instead of being listed as such is listed as Raid:Raid Ready. Something the way this computer is set up is preventing Ubuntu from being able to identify the hard drive partitions at all to do an install, even if you were not doing a dual boot and just wanted to overwrite Windows. Is this a bug that needs reported? This is a major problem for me and my brother, but also for Ubuntu if new users want to Ubuntu and find they cannot install it.

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  • creating a pre-menu level select screen

    - by Ephiras
    Hi I am working on creating a tower Defence java applet game and have come to a road block about implementing a title screen that i can select the level and difficulty of the rest of the game. my title screen class is called Menu. from this menu class i need to pass in many different variables into my Main class. i have used different classes before and know how to run them and such. but if both classes extend applet and each has its individual graphics method how can i run things from Main even though it was created in Menu. what i essentially want to do is run the Menu class withits action listeners and graphics until a Difficulty button has been selected, run the main class (which 100% works without having to have the Menu class) and pretty much terminate Menu so that i cannot go back to it, do not see its buttons or graphics menus. can i run one applet annd when i choose a button close that one and launch the other one? IF you would like to download the full project you can find it here, i had to comment out all the code that wasn't working my Menu class import java.awt.*; import java.awt.event.*; import java.applet.*; public class Menu extends Applet implements ActionListener{ Button bEasy,bMed,bHard; Main m; public void init(){ bEasy= new Button("Easy"); bEasy.setBounds(140,200,100,50); add(bEasy); bMed = new Button("Medium");bMed.setBounds(280,200,100,50); add(bMed); bHard= new Button("Hard");bHard.setBounds(420,200,100,50); add(bHard); setLayout(null); } public void actionPerformed(ActionEvent e){ Main m = new Main(20,10,3000,mapMed);//break; switch (e.getSource()){ case bEasy: Main m = new Main(6000,20,"levels/levelEasy.png");break;//enimies tower money world case bMed: Main m = new Main(4000,15,"levels/levelMed.png");break; case bHard: Main m = new Main(2000,10,"levels/levelEasy.png");break; default: break; } } public void paint(){ //m.draw(g) } } and here is my main class initialising code. import java.awt.*; import java.awt.event.*; import java.applet.*; import java.io.IOException; public class Main extends Applet implements Runnable, MouseListener, MouseMotionListener, ActionListener{ Button startButton, UpgRange, UpgDamage; //set up the buttons Color roadCol,startCol,finCol,selGrass,selRoad; //set up the colors Enemy e[][]; Tower t[]; Image towerpic,backpic,roadpic,levelPic; private Image i; private Graphics doubleG; //here is the world 0=grass 1=road 2=start 3=end int world[][],eStartX,eStartY; boolean drawMouse,gameEnd; static boolean start=false; static int gridLength=15; static int round=0; int Mx,My,timer=1500; static int sqrSize=31; int towers=0,towerSelected=-10; static int castleHealth=2000; String levelPath; //choose the level Easy Med or Hard int maxEnemy[] = {5,7,12,20,30,15,50,30,40,60};//number of enimies per round int maxTowers=15;//maximum number of towers allowed static int money =2000,damPrice=600,ranPrice=350,towerPrice=700; //money = the intial ammount of money you start of with //damPrice is the price to increase the damage of a tower //ranPrice is the price to increase the range of a tower public void main(int cH,int mT,int mo,int dP,int rP,int tP,String path,int[] mE)//constructor 1 castleHealth=cH; maxTowers=mT; money=mo; damPrice=dP; ranPrice=rP; towerPrice=tP; String levelPath=path; maxEnemy = mE; buildLevel(); } public void main(int cH,int mT,String path)//basic constructor castleHealth=cH; maxTowers=mT; String levelPath=path; maxEnemy = mE; buildLevel(); } public void init(){ setSize(sqrSize*15+200,sqrSize*15);//set the size of the screen roadCol = new Color(255,216,0);//set the colors for the different objects startCol = new Color(0,38,255); finCol = new Color(255,0,0); selRoad = new Color(242,204,155);//selColor is the color of something when your mouse hovers over it selGrass = new Color(0,190,0); roadpic = getImage(getDocumentBase(),"images/road.jpg"); towerpic = getImage(getDocumentBase(),"images/tower.png"); backpic = getImage(getDocumentBase(),"images/grass.jpg"); levelPic = getImage(getDocumentBase(),"images/level.jpg"); e= new Enemy[maxEnemy.length][];//activates all of the enimies for (int r=0;r<e.length;r++) e[r] = new Enemy[maxEnemy[r]]; t= new Tower[maxTowers]; for (int i=0;i<t.length;i++) t[i]= new Tower();//activates all the towers for (int i=0;i<e.length; i++)//sets all of the enimies starting co ordinates for (int j=0;j<e[i].length;j++) e[i][j] = new Enemy(eStartX,eStartY,world); initButtons();//initialise all the buttons addMouseMotionListener(this); addMouseListener(this); }

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  • KVM Virtual guest Paused on Reboot

    - by David Hamilton
    I'm running REHL 6 and just installed a Ubuntu Server Guest via KVM set to start at boot. This works correctly and the guest loads, but it loads "paused" and requires that I manually un-pause it. Can someone give me a hint as to how I can I get the Guest OS to actually become active on boot? Here is the libvert dump as requested...Also tried libvert auto-start --- no effect. <domain type='kvm' id='1'> <name>MailServer</name> <uuid>a61dae75-1f5c-d536-718f-3c615d9b4868</uuid> <memory>4194304</memory> <currentMemory>4194304</currentMemory> <vcpu>4</vcpu> <os> <type arch='x86_64' machine='rhel6.0.0'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> <pae/> </features> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>restart</on_crash> <devices> <emulator>/usr/libexec/qemu-kvm</emulator> <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source file='/home/MailServer/MailServer-1.img'/> <target dev='hda' bus='ide'/> <alias name='ide0-0-0'/> <address type='drive' controller='0' bus='0' unit='0'/> </disk> <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='hdc' bus='ide'/> <readonly/> <alias name='ide0-1-0'/> <address type='drive' controller='0' bus='1' unit='0'/> </disk> <controller type='ide' index='0'> <alias name='ide0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> </controller> <interface type='bridge'> <mac address='52:54:00:cd:f9:9f'/> <source bridge='br0'/> <target dev='vnet0'/> <model type='virtio'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> <serial type='pty'> <source path='/dev/pts/1'/> <target port='0'/> <alias name='serial0'/> </serial> <console type='pty' tty='/dev/pts/1'> <source path='/dev/pts/1'/> <target port='0'/> <alias name='serial0'/> </console> <input type='mouse' bus='ps2'/> <graphics type='vnc' port='5900' autoport='yes'/> <sound model='ac97'> <alias name='sound0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> </sound> <video> <model type='cirrus' vram='9216' heads='1'/> <alias name='video0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </video> <memballoon model='virtio'> <alias name='balloon0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </memballoon> </devices> <seclabel type='dynamic' model='selinux'> <label>system_u:system_r:svirt_t:s0:c211,c271</label> <imagelabel>system_u:object_r:svirt_image_t:s0:c211,c271</imagelabel> </seclabel></domain>

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  • Windows 7 can't boot with Ubuntu on different hard drive

    - by dellphi
    I use a dual boot with two hard disks and two OS is Ubuntu 10.04 and Windows 7. Windows 7 installed on the first disk, first partition. Grub is installed on a second hard disk MBR, and Ubuntu installed on an extended partition on a second hard drive. When I select Windows 7 on the Grub menu, the HDD lamp lights up briefly and then black screen on the monitor, with the status of the keyboard is still functioning. Until now (with the default boot from first HDD), I have to press F12 to get into the Grub to run Linux on a second HDD. output of fdisk -l grub.cfg. I want to retain Grub to remain on the second HDD, and Windows 7 could choose from the menu provided by Grub. But I do not get how, I hope anyone can help.

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  • installed ubuntu 13.04 but no wireless or wired connection available

    - by James
    after having installed ubuntu 13.04 i can not connect to the internet wirelessly or wired? can only connect to internet by using "try ubuntu" via ethernet cable, ive tried seeking help in so many different ways yet getting no positive outcome at all, will someone please explain why i can only connect with ethernet while i have the cd in the tray? ive also tried downloading b43 drivers to connect to the internet but apparently i dont have enough disk space, what is going on here? i have the disk in the tray now at the screen where you can either try or install, if someone could give me a step by step from here it would probably cut out all this hassle of me not knowing whats going on

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  • How can I avoid the random restart of the xserver?

    - by Bernd
    I'm using a desktop pc with 64bit Ubuntu 12.04 (Kernel 3.2.0-24-generic). Hardware specs are - Intel Core i7 CPU 860 @ 2,80GHz x 8 - Nvidia GeForce GTS 250 - 750 GB Hard Disk ATA WDC WD7501AALS-00E3A0 (for my /home partition) - 128 GB Solid-State Disk ATA PLEXTOR PX-128M2S (for all other partitions) Since I reinstalled the PC with Ubuntu 12.04 the xserver restarts randomly. Most times when I watch a video in the browser (maybe a flash issue?) but sometimes the restart/crash appears when I'm working in an text-editor. How can I locate the problem? Which information is needed for a useful answer?

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  • Unreal 3 Editor (Unreal Tournament 3) Why does the X Y Z translations now rotate along with my static meshes?

    - by Gareth Jones
    So I was making a map for UT3, using the Unreal 3 Editor provided, and all was going well. However I was doing some work with InterpActors and Vehicle Spawners, when I must have hit a key by mistake (or other wise somehow changed something) by mistake. Now the X Y Z translations that are used to move objects around in the editor will rotate along with the object (Ive put images down below to help show what I mean) - This is very annoying because it also changes the direction the arrow keys move a rotated object, in the example below, the Down arrow key will now move the object to the right. How can I fix this? (Note both images are taken from the same viewpoint) Before Rotation: After Rotation: P.S. If someone could please provide me with the correct / better name for the X Y Z "things" it would be much appreciated, thanks!

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  • Decrease filesize when resizing with mogrify

    - by plua
    I love the command line options of imagemagick. Mogrify is great to resize images and change quality, which is what I use most often. However, I have noted that the filesize if often larger than what it should be. Especially with small images. For instance, I have a regular 640px (width) photo, which I change to quality 80 and a width of 80px: mogrify -quality 80 -resize 80 file.jpg Works well and my image gets resized and the quality is changed to 80. However, the filesize is around 40Kb. For such a tiny image, that is huge! When I use mtPaint, and open the file and save it (not changing anything, just CTRL+O, CTRL+S), the filesize decreases with more than 95% to less than 2Kb! I have seen this is often the case. What goes wrong?

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  • Can't see my partitions after grub recovery

    - by dimbo
    I stupidly inserted the windows CD into my dual boot Ubuntu 11.10 / windows xp system. I just wanted to see if I could install windows on my external usb HD, but didn't actually go ahead with the install. It seems like the windows CD messed up my MBR and I had to use boot-repair and the ubuntu 11.10 live CD to gain access to ubuntu again. It seems to boot up a little differently (slower) but works. However, I now cant see any of my partitions in nautilus (there are 3). When I open gparted, it just shows my whole hard drive as unallocated (I know it has a windows partition that works and my ubuntu partition that I am using now). If I insert a usb pen, it is also not visible in nautilus but in gparted shows up as a FAT32 partition (which is correct although I cannot access it). sudo fdisk -l gives the following : demian@dimbo-TP:~$ sudo fdisk -l [sudo] password for demian: omitting empty partition (5) Disk /dev/sda: 320.1 GB, 320072933376 bytes 240 heads, 63 sectors/track, 41345 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x877b877b Device Boot Start End Blocks Id System /dev/sda1 * 63 63842309 31921123+ 7 HPFS/NTFS/exFAT /dev/sda2 63844350 133484084 34819867+ 5 Extended /dev/sda3 127636488 133484084 2923798+ 82 Linux swap / Solaris /dev/sda4 133484085 625137344 245826630 83 Linux /dev/sda5 63844352 123445247 29800448 83 Linux /dev/sda6 123447296 127635455 2094080 82 Linux swap / Solaris Disk /dev/sdb: 8100 MB, 8100249600 bytes 12 heads, 40 sectors/track, 32960 cylinders, total 15820800 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xc3072e18 Device Boot Start End Blocks Id System /dev/sdb1 * 5992 15820799 7907404 c W95 FAT32 (LBA) Here is my grub.conf file. Like I said before, I had to use the 'boot-repair' utility with the live cd to get grub working again. I think that this utility maybe created a new grub for me because the startup is definitely not the same. The screen goes blank for a while, and then the ubuntu loading dots come up for a brief moment (instead of during the whole startup process) before the dektop is displayed. Anyway : # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga insmod video_bochs insmod video_cirrus } insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=auto load_video insmod gfxterm insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a set locale_dir=($root)/boot/grub/locale set lang=en_US insmod gettext fi terminal_output gfxterm if [ "${recordfail}" = 1 ]; then set timeout=10 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray if background_color 44,0,30; then clear fi ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### if [ ${recordfail} != 1 ]; then if [ -e ${prefix}/gfxblacklist.txt ]; then if hwmatch ${prefix}/gfxblacklist.txt 3; then if [ ${match} = 0 ]; then set linux_gfx_mode=keep else set linux_gfx_mode=text fi else set linux_gfx_mode=text fi else set linux_gfx_mode=keep fi else set linux_gfx_mode=text fi export linux_gfx_mode if [ "$linux_gfx_mode" != "text" ]; then load_video; fi menuentry 'Ubuntu, with Linux 3.0.0-12-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail set gfxpayload=$linux_gfx_mode insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a linux /boot/vmlinuz-3.0.0-12-generic root=UUID=5349ff67-b7b7-489f-a881-ae49c1dcd84a ro quiet splash vt.handoff=7 initrd /boot/initrd.img-3.0.0-12-generic } menuentry 'Ubuntu, with Linux 3.0.0-12-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod gzio insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a echo 'Loading Linux 3.0.0-12-generic ...' linux /boot/vmlinuz-3.0.0-12-generic root=UUID=5349ff67-b7b7-489f-a881-ae49c1dcd84a ro recovery nomodeset echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-3.0.0-12-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(hd0,msdos6)' search --no-floppy --fs-uuid --set=root 5349ff67-b7b7-489f-a881-ae49c1dcd84a linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Microsoft Windows XP Professional (on /dev/sda1)" --class windows --class os { insmod part_msdos insmod ntfs set root='(hd0,msdos1)' search --no-floppy --fs-uuid --set=root 72A89361A89322A1 drivemap -s (hd0) ${root} chainloader +1 } ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ### How can I get things back to normal. Thanks, Demian.

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  • Of transactions and Mongo

    - by Nuri Halperin
    Originally posted on: http://geekswithblogs.net/nuri/archive/2014/05/20/of-transactions-and-mongo-again.aspxWhat's the first thing you hear about NoSQL databases? That they lose your data? That there's no transactions? No joins? No hope for "real" applications? Well, you *should* be wondering whether a certain of database is the right one for your job. But if you do so, you should be wondering that about "traditional" databases as well! In the spirit of exploration let's take a look at a common challenge: You are a bank. You have customers with accounts. Customer A wants to pay B. You want to allow that only if A can cover the amount being transferred. Let's looks at the problem without any context of any database engine in mind. What would you do? How would you ensure that the amount transfer is done "properly"? Would you prevent a "transaction" from taking place unless A can cover the amount? There are several options: Prevent any change to A's account while the transfer is taking place. That boils down to locking. Apply the change, and allow A's balance to go below zero. Charge person A some interest on the negative balance. Not friendly, but certainly a choice. Don't do either. Options 1 and 2 are difficult to attain in the NoSQL world. Mongo won't save you headaches here either. Option 3 looks a bit harsh. But here's where this can go: ledger. See, and account doesn't need to be represented by a single row in a table of all accounts with only the current balance on it. More often than not, accounting systems use ledgers. And entries in ledgers - as it turns out – don't actually get updated. Once a ledger entry is written, it is not removed or altered. A transaction is represented by an entry in the ledger stating and amount withdrawn from A's account and an entry in the ledger stating an addition of said amount to B's account. For sake of space-saving, that entry in the ledger can happen using one entry. Think {Timestamp, FromAccountId, ToAccountId, Amount}. The implication of the original question – "how do you enforce non-negative balance rule" then boils down to: Insert entry in ledger Run validation of recent entries Insert reverse entry to roll back transaction if validation failed. What is validation? Sum up the transactions that A's account has (all deposits and debits), and ensure the balance is positive. For sake of efficiency, one can roll up transactions and "close the book" on transactions with a pseudo entry stating balance as of midnight or something. This lets you avoid doing math on the fly on too many transactions. You simply run from the latest "approved balance" marker to date. But that's an optimization, and premature optimizations are the root of (some? most?) evil.. Back to some nagging questions though: "But mongo is only eventually consistent!" Well, yes, kind of. It's not actually true that Mongo has not transactions. It would be more descriptive to say that Mongo's transaction scope is a single document in a single collection. A write to a Mongo document happens completely or not at all. So although it is true that you can't update more than one documents "at the same time" under a "transaction" umbrella as an atomic update, it is NOT true that there' is no isolation. So a competition between two concurrent updates is completely coherent and the writes will be serialized. They will not scribble on the same document at the same time. In our case - in choosing a ledger approach - we're not even trying to "update" a document, we're simply adding a document to a collection. So there goes the "no transaction" issue. Now let's turn our attention to consistency. What you should know about mongo is that at any given moment, only on member of a replica set is writable. This means that the writable instance in a set of replicated instances always has "the truth". There could be a replication lag such that a reader going to one of the replicas still sees "old" state of a collection or document. But in our ledger case, things fall nicely into place: Run your validation against the writable instance. It is guaranteed to have a ledger either with (after) or without (before) the ledger entry got written. No funky states. Again, the ledger writing *adds* a document, so there's no inconsistent document state to be had either way. Next, we might worry about data loss. Here, mongo offers several write-concerns. Write-concern in Mongo is a mode that marshals how uptight you want the db engine to be about actually persisting a document write to disk before it reports to the application that it is "done". The most volatile, is to say you don't care. In that case, mongo would just accept your write command and say back "thanks" with no guarantee of persistence. If the server loses power at the wrong moment, it may have said "ok" but actually no written the data to disk. That's kind of bad. Don't do that with data you care about. It may be good for votes on a pole regarding how cute a furry animal is, but not so good for business. There are several other write-concerns varying from flushing the write to the disk of the writable instance, flushing to disk on several members of the replica set, a majority of the replica set or all of the members of a replica set. The former choice is the quickest, as no network coordination is required besides the main writable instance. The others impose extra network and time cost. Depending on your tolerance for latency and read-lag, you will face a choice of what works for you. It's really important to understand that no data loss occurs once a document is flushed to an instance. The record is on disk at that point. From that point on, backup strategies and disaster recovery are your worry, not loss of power to the writable machine. This scenario is not different from a relational database at that point. Where does this leave us? Oh, yes. Eventual consistency. By now, we ensured that the "source of truth" instance has the correct data, persisted and coherent. But because of lag, the app may have gone to the writable instance, performed the update and then gone to a replica and looked at the ledger there before the transaction replicated. Here are 2 options to deal with this. Similar to write concerns, mongo support read preferences. An app may choose to read only from the writable instance. This is not an awesome choice to make for every ready, because it just burdens the one instance, and doesn't make use of the other read-only servers. But this choice can be made on a query by query basis. So for the app that our person A is using, we can have person A issue the transfer command to B, and then if that same app is going to immediately as "are we there yet?" we'll query that same writable instance. But B and anyone else in the world can just chill and read from the read-only instance. They have no basis to expect that the ledger has just been written to. So as far as they know, the transaction hasn't happened until they see it appear later. We can further relax the demand by creating application UI that reacts to a write command with "thank you, we will post it shortly" instead of "thank you, we just did everything and here's the new balance". This is a very powerful thing. UI design for highly scalable systems can't insist that the all databases be locked just to paint an "all done" on screen. People understand. They were trained by many online businesses already that your placing of an order does not mean that your product is already outside your door waiting (yes, I know, large retailers are working on it... but were' not there yet). The second thing we can do, is add some artificial delay to a transaction's visibility on the ledger. The way that works is simply adding some logic such that the query against the ledger never nets a transaction for customers newer than say 15 minutes and who's validation flag is not set. This buys us time 2 ways: Replication can catch up to all instances by then, and validation rules can run and determine if this transaction should be "negated" with a compensating transaction. In case we do need to "roll back" the transaction, the backend system can place the timestamp of the compensating transaction at the exact same time or 1ms after the original one. Effectively, once A or B visits their ledger, both transactions would be visible and the overall balance "as of now" would reflect no change.  The 2 transactions (attempted/ reverted) would be visible , since we do actually account for the attempt. Hold on a second. There's a hole in the story: what if several transfers from A to some accounts are registered, and 2 independent validators attempt to compute the balance concurrently? Is there a chance that both would conclude non-sufficient-funds even though rolling back transaction 100 would free up enough for transaction 117 (some random later transaction)? Yes. there is that chance. But the integrity of the business rule is not compromised, since the prime rule is don't dispense money you don't have. To minimize or eliminate this scenario, we can also assign a single validation process per origin account. This may seem non-scalable, but it can easily be done as a "sharded" distribution. Say we have 11 validation threads (or processing nodes etc.). We divide the account number space such that each validator is exclusively responsible for a certain range of account numbers. Sounds cunningly similar to Mongo's sharding strategy, doesn't it? Each validator then works in isolation. More capacity needed? Chop the account space into more chunks. So where  are we now with the nagging questions? "No joins": Huh? What are those for? "No transactions": You mean no cross-collection and no cross-document transactions? Granted - but don't always need them either. "No hope for real applications": well... There are more issues and edge cases to slog through, I'm sure. But hopefully this gives you some ideas of how to solve common problems without distributed locking and relational databases. But then again, you can choose relational databases if they suit your problem.

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  • How to Estimate Needed Bandwidth for New Web Application?

    - by Noah Goodrich
    I am working on a brand new SaaS web application and need to estimate the initial bandwidth usage. Since the site doesn't exist yet, and since this is my first endeavor of this sort, I'm not really sure how much bandwidth to estimate to begin with. We will be using Linux, Apache, PHP and Mysql. The content will be generated dynamically. There will be images as part of the site design but user's will also upload images that will be displayed and documents that will be stored for download at later times. We'd like to be able to support 500,000 page loads per month with estimated image loads being about two to three times that.

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  • How do I change the volume control icon?

    - by Richard Oren Pincook
    I recently switched to gnome 3 (love it!), but the default icon theme was a little dreary and gray, so I switched that back to ubuntu-mono-dark. But now whenever I change my volume, I get this ugly pixelated icon show up. The forum says I don't have enough reputation to post an screenshot, but it's pixelated and ugly with these fuzzy straight blue lines that turn on as the volume goes up. I found identical images in the Humanity and Humanity-Dark icon themes (one example: /usr/share/icons/Humanity/status/24/audio-volume-high.png). I tinkered with the images by changing their names, temporarily deleting them, etc. But it had no effect on the ugly icon. What file is responsible for violating the beauty of my desktop?! Once I find it, I can replace it.

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  • Fix Windows MBR using Ubuntu Live CD

    - by kova
    I'm trying to fix the MBR using Ubuntu live CD. I already have the ms-sys installed but from the threads that I saw, I'm not completely sure in which /dev I should execute the command: sudo ms-sys --mbr7 /dev/??? (is it mbr7 the correct option when using Windows 7?) ubuntu@ubuntu:~$ sudo fdisk -l Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x1f205b1f Device Boot Start End Blocks Id System /dev/sda1 * 38 38 0 0 Empty /dev/sda2 * 2048 206847 102400 7 HPFS/NTFS/exFAT /dev/sda3 206848 155854847 77824000 7 HPFS/NTFS/exFAT /dev/sda4 155854848 625137663 234641408 7 HPFS/NTFS/exFAT ubuntu@ubuntu:~$ Why is /dev/sda1 empty? I'm trying to fix the MBR because I'm getting a black screen when trying to load the operating system.

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  • ssrs: the report execution has expired or cannot be found

    - by Alex Bransky
    Today I got an exception in a report using SQL Server Reporting Services 2008 R2, but only when attempting to go to the last page of a large report: The report execution sgjahs45wg5vkmi05lq4zaee has expired or cannot be found.;Digging into the logs I found this:library!ReportServer_0-47!149c!12/06/2012-12:37:58:: e ERROR: Throwing Microsoft.ReportingServices.Diagnostics.Utilities.ReportServerStorageException: , An error occurred within the report server database.  This may be due to a connection failure, timeout or low disk condition within the database.;I knew it wasn't a network problem or timeout because I could repeat the problem at will.  I checked the disk space and that seemed fine as well.  The real issue was a lack of memory on the database server that had the ReportServer database.  Restarting the SQL Server engine freed up plenty of RAM and the problem immediately went away.

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  • Dual Boot Ubuntu and Windows 7: BOOTMGR is missing when I tried to boot in Windows

    - by Simon Polak
    So, I don't know what exactly how I managed to delete the MBR record on windows partition. But let me explain what I did next, I ran the ubuntu boot repair tool and now Windows is not even listed in my grub loader. So I went and booted with windows cd and choose repair. Then I ran ubuntu boot repair again via live cd. Here is the log http://paste.ubuntu.com/1426181/. Still no luck. Looks like osprobe can't detect windows on my /dev/sda2 partition. Any clues ? Here is how my partitions look like: Disk /dev/sda: 500.1 GB, 500107862016 bytes 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x525400d1 Device Boot Start End Blocks Id System /dev/sda1 * 2048 206847 102400 7 HPFS/NTFS/exFAT /dev/sda2 206848 509620669 254706911 7 HPFS/NTFS/exFAT /dev/sda3 509622270 976773119 233575425 5 Extended /dev/sda5 509622272 957757439 224067584 83 Linux /dev/sda6 957759488 976773119 9506816 82 Linux swap / Solaris

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  • Drawing an outline around an arbitrary group of hexagons

    - by Perky
    Is there an algorithm for drawing an outline around around an arbitrary group of hexagons? The polygon outline drawn may be concave. See the images below, the green line is what I am trying to achieve. The hexagons are stored as vertices and drawn as polygons. Edit: I've uploaded images that should explain more. I want to favour convex hulls because it's conveys an area of control more quickly. Each hexagon is stored in a multidimensional array so they all have x and y coordinates, I can easily find adjacent hexagons and the opposite vertex, i.e. adjacentHexagon = getAdjacentHexagon( someHexagon, NORTHWEST ) if there isn't a hexagon immediately adjacent it will continue to search in that direction until it finds one or hits the map edges.

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