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• Silverlight Cream for February 09, 2011 -- #1044

  - by Dave Campbell

  In this Issue: Vikas, Tony Champion, Peter Kuhn, Ollie Riches, Rich Griffin, Rob Eisenberg, Andrea Boschin, Rudi Grobler(-2-), Jesse Liberty, Dan Wahlin, Roberto Sonnino, Deborah Kurata. Above the Fold: Silverlight: "Silverlight double click event" Vikas WP7: "Logging in Silverlight and WP7 with MVVM Light" Tony Champion XNA: "XNA for Silverlight developers: Part 3 - Animation (transforms)" Peter Kuhn Shoutouts: Vikas deserves congratulations for passing the beta Silverlight 4 exam, but in the process he has a great list of resources to help you do the same: Exam 70-506 ( TS: Silverlight 4, Development ) From SilverlightCream.com: Silverlight double click event Vikas demonstrates 3 ways to come up with a double-click in Silverlight: Timer, Rx Framework, and Behavior with code for each. Logging in Silverlight and WP7 with MVVM Light Tony Champion is discussing logging... and since he finds himself doing it in every project, he's setting up an extensible solution he can reuse and is doing so with MVVMLight XNA for Silverlight developers: Part 3 - Animation (transforms) Peter Kuhn has part 3 of his XNA for WP7 series up at SilverlightShow. In this 3rd tutorial, Peter is discussing animation with Transformations.... remember... this is XNA! WP7Contrib: Location Push Model Ollie Riches posts from the WP7C and discusses how they provide an interface for location service by abstracting away the GeoCoordinateWatcher class and provide a clean push model using the IObservable as the return types for all variants. WP7 Contrib – When messaging becomes messy and services shine Rich Griffin pulls another post up from WP7C where he discusses swapping out using Service Styles rather than Messenger Styles... in his words "when we start getting friction trying to bend the framework api to do something that it was not really meant for its time to use something [that] solves the problem better" Herding Code 104: Rob Eisenberg on Caliburn Micro Rob Eisenberg is interviewed on the latest Herding Code, talking about his baby, Caliburn Micro, and tons of other stuff as well... just check out the list of links generated for this show. Windows Phone 7 - Part #4: The application lifecycle Andrea Boschin has part 4 of his WP7 tutorial series up at SilverlightShow... In this tutorial he does a complete run-down the the WP7 Application Life-Cycle Simple Error Reporting on WP7 Rudi Grobler has a code snippet up that, with the end-user's permission of course, emails problem reports back to you... very cool idea. Simple Error Reporting on WP7 REDUX Rudi Grobler demonstrates using the Coding4Fun toolkit to display an exception prompt to the user... and then possibly email the report to you..see Rudi's other post on that. Creating An Application Bar–Don’t Panic In his latest (number 31) WP7 From Scratch episode, Jesse Liberty takes on the ApplicationBar, and uses Blend to get the job done easier. Syncing Data with a Server using Silverlight and HTTP Polling Duplex Dan Wahlin revisits some older posts of his about Push technologies in Silverlight, and provides some great insight (and code) into Http Polling Duplex Quick WPF/Silverlight tips to make great videos of your apps Roberto Sonnino has some great tips on making awesome videos of your WPF or Silverlight app. Simple Silverlight MVVM Base Class Deborah Kurata has her take at a good MVVM base class as the subject of her latest post... good points and good code. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• Restoring an Ubuntu Server using ZFS RAIDZ for data

  - by andybjackson

  Having become disillusioned with hacking Buffalo NAS devices, I've decided to roll my own Home server. After some research, I have settled on an HP Proliant Microserver with Ubuntu Server and ZFS (OS on 1 Ext4 disk, Data on 3 RAIDZ disks). As Joel Spolsky and Geoff Atwood say with regards to backup, I can't rest until I have done a restore in all of the failure scenarios that I am seeking to protect against. Q: How to configure Ubuntu Server to recognise a pre-existing RAIDZ array? Clearly if one of the data disks die - then that is a resilvering scenario, which is well documented. If two of the data disks die, then I am into regular backup/restore land. If the OS dies and I can restore, also an easy scenario. But if the OS dies and I can't restore, then I need to recreate an Ubuntu server. But how do I get this to recognise my RAID-Z array? Is the necessary configuration information stored within and across the RAIZ array and simply need to be found (if so, how)? Or does it reside on the OS ext4 disk (in which case how do I recreate it)?

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• What effect does RAID stripe size have on read-ahead settings?

  - by stbrody

  I'm trying to figure out the correct read-ahead values to set on a RAID10 array, and I'm wondering if the RAID stripe size should factor into my considerations. I've heard conflicting information about this in the past. I once heard that you should always set your read-ahead value to a multiple of the RAID stripe size, and never below the stripe size, because that is the minimum amount of data the RAID controller will ever try to read at once. Someone else told me, however, that setting read-ahead below the stripe size is fine, and can, in fact, increase the amount of parallel reads you can do across devices in the array, increasing performance and decreasing load on the array. So which is it? Do read-ahead settings that aren't multiples of the stripe size make sense or not?

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• Correct For Loop Design

  - by Yttrill

  What is the correct design for a for loop? Felix currently uses if len a > 0 do for var i in 0 upto len a - 1 do println a.[i]; done done which is inclusive of the upper bound. This is necessary to support the full range of values of a typical integer type. However the for loop shown does not support zero length arrays, hence the special test, nor will the subtraction of 1 work convincingly if the length of the array is equal to the number of integers. (I say convincingly because it may be that 0 - 1 = maxval: this is true in C for unsigned int, but are you sure it is true for unsigned char without thinking carefully about integral promotions?) The actual implementation of the for loop by my compiler does correctly handle 0 but this requires two tests to implement the loop: continue: if not (i <= bound) goto break body if i == bound goto break ++i goto continue break: Throw in the hand coded zero check in the array example and three tests are needed. If the loop were exclusive it would handle zero properly, avoiding the special test, but there'd be no way to express the upper bound of an array with maximum size. Note the C way of doing this: for(i=0; predicate(i); increment(i)) has the same problem. The predicate is tested after the increment, but the terminating increment is not universally valid! There is a general argument that a simple exclusive loop is enough: promote the index to a large type to prevent overflow, and assume no one will ever loop to the maximum value of this type.. but I'm not entirely convinced: if you promoted to C's size_t and looped from the second largest value to the largest you'd get an infinite loop!

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• Suggestions for a CMS markup language for PHP

  - by Yanick Rochon

  As a learning experience, and as project, I am attempting to write a CMS module for ZF2. One of the functionality I would like to have is the possibility of adding dynamic contents in the pages by calling PHP functions in the view scripts. However, I do not want to give the users freedom in writing PHP code directly inside the page content, but rather implement custom view helpers (or widgets) to handle logic. For example: calling partial, partialLoop, url, etc. specifying arguments and all. I liked the idea of extending Markdown but this would get complicated when trying to add custom CSS class to elements, etc. Then I had the idea of simply doing a preg_replace on some patterns. For example, the string : ### partialLoop:['partials/display.phtml',[{id:'p1',price:4.99},{id:'p2',price:12.34}]] ### would be replaced by <?php echo $this->partialLoop('partials/display.phtml', array(array('id'=>'p1','price'=>4.99),array('id'=>'p2','price'=>12.34))) ?> Obviously, there would be some caching done so the page content is not rendered everytime. Does this sound good? If not, what would be a good way of doing this? Or is there a project already being developed for doing this? (I'd like to avoid heavy third party libs and something fairly or fully compatible with ZF2 would be nice.) Thanks.

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• Share Folders & Files Between Vista and XP Machines

  - by Mysticgeek

  Since Microsoft has three operating systems in use, chances are you’ll find yourself needing to share files between XP, Vista, Windows 7, or some combination of the three. Here we take a look at sharing between a Vista and XP on your home network. Share Without Password Protected Sharing If you’re not worried about who’s accessing the files and folders, the easiest method is to disable Password Protected Sharing. So on the Vista machine open Network and Sharing Center. Under Sharing and Discovery make sure Network Discovery, File Sharing, and, Public Folder Sharing are turned on. Also turn off Password Protected Sharing… Now go into the Vista Public folder, located in C:\Users\Public, and add what you want to share or create a new folder. In this example we created a new folder called XP_Share and added some files to it. On the XP machine go into My Network Places and under Network Tasks click on View Workgroup Computers. Now you’ll see all of the computers on your network which should be part of the same Workgroup. Here we need to double-click on the Vista computer. And there we go…no password to enter so we can access the XP_Share folder or anything else that is located in the Public folder. Share with Password Protected Sharing If you want to keep Password Protected Sharing turned on, then we need to do things a little different. When it’s turned on and you try to access the Vista machine from XP, you’re prompted for a password, and no matter what you think the credentials are, you can’t get access…very annoying. So what we need to do is add the XP Machine as a user. Right-click on Computer from the Start Menu or desktop icon and select Manage from the context menu. The Computer Management screen opens up and you want to expand Local Users and Groups, then the Users folder. Then right-click any open area an select New User. Now create a new user name and password, you can also fill in the other fields if you want. Then make sure to uncheck User must change password at next logon and check the box next to Password never expires. Click the Create button and close out of the New User screen. You’ll then see the new user we created in the list and you can close out of the Computer Management window. Now back on the XP computer when you double-click on the Vista machine, your prompted to log in. Just type in the username and password you just created. Now you’ll have access to the Public folder contents. Set up Sharing on XP If you want to access a shared folder from the Vista computer located on the XP machine, it’s the same process in reverse. On the XP computer in Shared Documents, right-click on the folder you want to share and select Sharing and Security. Then select the radio button next to Share this folder and click Ok. Go into Computer Management and create a new user… Now from the Vista machine double click on the XP machine icon, enter the password, then access the folders and files you need. If you have multiple versions of Windows on your home network, you’ll now be able to access files and folders from each of them. If you want to share between Windows 7 and XP check out our article on how to share files and printers between Windows 7 and XP. You might also want to check out our article on how to share files and printers between Windows 7 and Vista. Similar Articles Productive Geek Tips Show Hidden Files and Folders in Windows 7 or VistaHow To Share Files and Printers Between Windows 7 and VistaShare Files and Printers between Windows 7 and XPHow To Share a Folder the XP Way in Windows VistaMoving Your Personal Data Folders in Windows Vista the Easy Way TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Scan your PC for nasties with Panda ActiveScan CleanMem – Memory Cleaner AceStock – The Personal Stock Monitor Add Multiple Tabs to Office Programs The Wearing of the Green – St. Patrick’s Day Theme (Firefox) Perform a Background Check on Yourself

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• Error using SoapClient() in PHP [migrated]

  - by Dhaval

  I'm trying to access WSDL(Web Service Definition Language) file using SoapClient() of PHP. I found that WSDL file is authenticated. I tried with passing credentials on an array by another parameter and active SSL on my server, still I'm getting an error. Here is the code I'm using: $client = new SoapClient("https://webservices.chargepointportal.net:8081/coulomb_api_1.1.wsdl",array("trace" = "1","Username" = "username","Password" = "password")); Here is the error I'm getting: Warning: SoapClient::SoapClient(https://webservices.chargepointportal.net:8081/coulomb_api_1.1.wsdl) [soapclient.soapclient]: failed to open stream: Connection timed out in PATH_TO_FILE on line 80 Warning: SoapClient::SoapClient() [soapclient.soapclient]: I/O warning : failed to load external entity "https://webservices.chargepointportal.net:8081/coulomb_api_1.1.wsdl" in PATH_TO_FILE on line 80 Fatal error: Uncaught SoapFault exception: [WSDL] SOAP-ERROR: Parsing WSDL: Couldn't load from 'https://webservices.chargepointportal.net:8081/coulomb_api_1.1.wsdl' : failed to load external entity "https://webservices.chargepointportal.net:8081/coulomb_api_1.1.wsdl" in PATH_TO_FILE:80 Stack trace: #0 /home2/wingstec/public_html/widget/API/index.php(80): SoapClient-SoapClient('https://webserv...', Array) #1 {main} thrown in PATH_TO_FILE on line 80 It seems that error says file not exist at the path we given but when we run that path directly on browser then we're getting that file Can anyone help me to figure out what the exactly problem is?

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• Distinct operator in Linq

  - by Jalpesh P. Vadgama

  Linq operator provides great flexibility and easy way of coding. Let’s again take one more example of distinct operator. As name suggest it will find the distinct elements from IEnumerable. Let’s take an example of array in console application and then we will again print array to see is it working or not. Below is the code for that. In this application I have integer array which contains duplicate elements and then I will apply distinct operator to this and then I will print again result of distinct operators to actually see whether its working or not. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Experiment { class Program { static void Main(string[] args) { int[] intArray = { 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5 }; var uniqueIntegers = intArray.Distinct(); foreach (var uInteger in uniqueIntegers) { Console.WriteLine(uInteger); } Console.ReadKey(); } } } Below is output as expected.. That’s cool..Stay tuned for more.. Happy programming. Technorati Tags: Linq,Distinct

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• need explanation on amortization in algorithm

  - by Pradeep

  I am a learning algorithm analysis and came across a analysis tool for understanding the running time of an algorithm with widely varying performance which is called as amortization. The autor quotes " An array with upper bound of n elements, with a fixed bound N, on it size. Operation clear takes O(n) time, since we should dereference all the elements in the array in order to really empty it. " The above statement is clear and valid. Now consider the next content: "Now consider a series of n operations on an initially empty array. if we take the worst case viewpoint, the running time is O(n^2), since the worst case of a sigle clear operation in the series is O(n) and there may be as many as O(n) clear operations in the series." From the above statement how is the time complexity O(n^2)? I did not understand the logic behind it. if 'n' operations are performed how is it O(n ^2)? Please explain what the autor is trying to convey..

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• Drawing multiple triangles at once isn't working

  - by Deukalion

  I'm trying to draw multiple triangles at once to make up a "shape". I have a class that has an array of VertexPositionColor, an array of Indexes (rendered by this Triangulation class): http://www.xnawiki.com/index.php/Polygon_Triangulation So, my "shape" has multiple points of VertexPositionColor but I can't render each triangle in the shape to "fill" the shape. It only draws the first triangle. struct ShapeColor { // Properties (not all properties) VertexPositionColor[] Points; int[] Indexes; } First method that I've tried, this should work since I iterate through the index array that always are of "3s", so they always contain at least one triangle. //render = ShapeColor for (int i = 0; i < render.Indexes.Length; i += 3) { device.DrawUserIndexedPrimitives<VertexPositionColor> ( PrimitiveType.TriangleList, new VertexPositionColor[] { render.Points[render.Indexes[i]], render.Points[render.Indexes[i+1]], render.Points[render.Indexes[i+2]] }, 0, 3, new int[] { 0, 1, 2 }, 0, 1 ); } or the method that should work: device.DrawUserIndexedPrimitives<VertexPositionColor> ( PrimitiveType.TriangleList, render.Points, 0, render.Points.Length, render.Indexes, 0, render.Indexes.Length / 3, VertexPositionColor.VertexDeclaration ); No matter what method I use this is the "typical" result from my Editor (in Windows Forms with XNA) It should show a filled shape, because the indexes are right (I've checked a dozen of times) I simply click the screen (gets the world coordinates, adds a point from a color, when there are 3 points or more it should start filling out the shape, it only draws the lines (different method) and only 1 triangle). The Grid isn't rendered with "this" shape. Any ideas?

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• Converting openGl code to DirectX

  - by Fredrik Boston Westman

  First of all, this is kind of a follow up question on @byte56 excellent anwser on this question concerning picking algorithms. I'm trying to convert one of his code examples to directX 11 however I have run in to some problems ( I can pick but the picking is way off), and I wanted to make sure I had done it rigth before moving on and checking the rest of my code. I am not that familiar with openGl but I can imagine openGl has diffrent coordinations systems, and functions that alters how you must implement to code abit. This is his code example: public Ray GetPickRay() { int mouseX = Mouse.getX(); int mouseY = WORLD.Byte56Game.getHeight() - Mouse.getY(); float windowWidth = WORLD.Byte56Game.getWidth(); float windowHeight = WORLD.Byte56Game.getHeight(); //get the mouse position in screenSpace coords double screenSpaceX = ((float) mouseX / (windowWidth / 2) - 1.0f) * aspectRatio; double screenSpaceY = (1.0f - (float) mouseY / (windowHeight / 2)); double viewRatio = Math.tan(((float) Math.PI / (180.f/ViewAngle) / 2.00f))* zoomFactor; screenSpaceX = screenSpaceX * viewRatio; screenSpaceY = screenSpaceY * viewRatio; //Find the far and near camera spaces Vector4f cameraSpaceNear = new Vector4f((float) (screenSpaceX * NearPlane), (float) (screenSpaceY * NearPlane), (float) (-NearPlane), 1); Vector4f cameraSpaceFar = new Vector4f((float) (screenSpaceX * FarPlane), (float) (screenSpaceY * FarPlane), (float) (-FarPlane), 1); //Unproject the 2D window into 3D to see where in 3D we're actually clicking Matrix4f tmpView = Matrix4f(view); Matrix4f invView = (Matrix4f) tmpView.invert(); Vector4f worldSpaceNear = new Vector4f(); Matrix4f.transform(invView, cameraSpaceNear, worldSpaceNear); Vector4f worldSpaceFar = new Vector4f(); Matrix4f.transform(invView, cameraSpaceFar, worldSpaceFar); //calculate the ray position and direction Vector3f rayPosition = new Vector3f(worldSpaceNear.x, worldSpaceNear.y, worldSpaceNear.z); Vector3f rayDirection = new Vector3f(worldSpaceFar.x - worldSpaceNear.x, worldSpaceFar.y - worldSpaceNear.y, worldSpaceFar.z - worldSpaceNear.z); rayDirection.normalise(); return new Ray(rayPosition, rayDirection); } All rigths reserved to him of course This is my DirectX 11 code : void GraphicEngine::pickRayVector(float mouseX, float mouseY,XMVECTOR& pickRayInWorldSpacePos, XMVECTOR& pickRayInWorldSpaceDir) { float PRVecX, PRVecY; float nearPlane = 0.1f; float farPlane = 200.0f; floar viewAngle = 0.4 * 3.14; PRVecX = ((( 2.0f * mouseX) / ClientWidth ) - 1 ) * tan((viewAngle)/2); PRVecY = (1-(( 2.0f * mouseY) / ClientHeight)) * tan((viewAngle)/2); XMVECTOR cameraSpaceNear = XMVectorSet(PRVecX * nearPlane,PRVecY * nearPlane, -nearPlane, 1.0f); XMVECTOR cameraSpaceFar = XMVectorSet(PRVecX * farPlane,PRVecY * farPlane, -farPlane, 1.0f); // Transform 3D Ray from View space to 3D ray in World space XMMATRIX invMat; XMVECTOR matInvDeter; invMat = XMMatrixInverse(&matInvDeter, cam->getCameraView()); //Inverse of View Space matrix is World space matrix XMVECTOR worldSpaceNear = XMVector3TransformCoord(cameraSpaceNear, invMat); XMVECTOR worldSpaceFar = XMVector3TransformCoord(cameraSpaceFar, invMat); pickRayInWorldSpacePos = worldSpaceNear; pickRayInWorldSpaceDir = worldSpaceFar-worldSpaceNear; pickRayInWorldSpaceDir = XMVector3Normalize(pickRayInWorldSpaceDir); } A couple of notes: The mouse coordinates are already converted so that the top left corner of the client window would be (0,0) and the bottom rigth (800,600) ( or whatever resolution you would have) I hadn't used any far or near plane before, so i just made some arbitrary number up for them. To my understanding it shouldnt matter as long as the object you are trying to pick is in between the range of thoese numbers The viewAngle is the same angle that I used when setting the camera view with XMMatrixPerspectiveFovLH , I just hadn't made it a member variable of my Camera class yet. I removed the variable aspectRation and zoomFactor because I assumed that they where related to some specific function of his game. Now I'm not sure, but I think the problems lies either withing the mouse to viewspace conversion, maby that we use diffrent coordinations systems. Either that or how i transform the matrixes in the the end, because i know order is important when it comes to matrixes. Any help is appriciated! Thanks in advance. Edit: One more note, my code is in c++

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• using php to list some files in folders

  - by Terix

  I have collected many free themes from around internet. Each of them has a screenshot.jpg or png file on their folder. I want to scan all the folders for that file, and return the full file path to be used with an img html tag. I am not interested on partial path or folders where there are not screenshots. For example, if my fodler structure is: ./a/b/ ./c/d/e/screenshot.jpg ./f/ ./g/screenshot.jpg ./h/i/j/k/ ./l/m/screenshot.png ./n/o/ ./p/screenshot.jpg I want to get: ./c/d/e/screenshot.jpg ./g/screenshot.jpg ./l/m/screenshot.png ./p/screenshot.jpg I managed somehow to get a recursive function, but I figured only the way to return an array and then i can't get rid of what I don't need, and I miss png. Can anyone help me on that? the code I managed to put together is this: function getDirectoryTree( $outerDir , $x){ $dirs = array_diff( scandir( $outerDir ), Array( ".", ".." ) ); $dir_array = Array(); foreach( $dirs as $d ){ if( is_dir($outerDir."/".$d) ){ $dir_array[ $d ] = getDirectoryTree( $outerDir."/".$d , $x); }else{ if ($d==x) $dir_array[ $d ] = $d; } } return $dir_array; } $dirlist = getDirectoryTree('.','screenshot.jpg'); print_r($dirlist);

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• Restoring an Ubuntu Server using ZFS RAID-Z for data

  - by andybjackson

  Having become disillusioned with hacking Buffalo NAS devices, I've decided to roll my own Home server. After some research, I have settled on an HP Proliant Microserver with Ubuntu Server and ZFS (OS on 1 Ext4 disk, Data on 3 RAID-Z disks). As Joel Spolsky and Geoff Atwood say with regards to backup, I can't rest until I have done a restore in all of the failure scenarios that I am seeking to protect against. Q: How to configure Ubuntu Server to recognise a pre-existing RAID-Z array? Clearly if one of the data disks die - then that is a resilvering scenario, which is well documented. If two of the data disks die, then I am into regular backup/restore land. If the OS dies and I can restore, also an easy scenario. But if the OS dies and I can't restore, then I need to recreate an Ubuntu server. But how do I get this to recognise my RAID-Z array? Is the necessary configuration information stored within and across the RAID-Z array and simply need to be found (if so, how)? Or does it reside on the OS ext4 disk (in which case how do I recreate it)?

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• Anyone tried dd'ing Raidmembers?

  - by DusteD

  I want replace all disks in a 10 disk raid6 (linux software raid). I could do this by pulling a disk, let the array rebuild, rinse, repeat. But this would take a very long time, and cause 10 rebuilds, which would most likely stress all 10 disks much more than simply reading each disk through once. My question is thus: Could I just shut down the array, and dd each old disk to a new disk and then start the array with the 10 new disks? In an ideal world, I would build another server and just copy the data via network, but this is not an ideal world.

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• Is there anyway to build a raid system without all drives?

  - by xenoterracide

  I'm building a raid1 (ok it will probably be a raid10,f2 but the difference with 2 drives... isn't much) system with 2 1TB drives. However, 1 of the drives I've ordered is bad so I'm RMA-ing it. I'm wondering if I could partition and install to the 1 drive and then rebuild the array when I get the second drive (after I test it of course) My initial investigation doesn't show me a way of creating the array without specifying all devices... and the device the second drive will be is one that has data that I will need to migrate (plus it's not big enough). Is it possible that I could create an array without specifying all devices? or specify false ones and reconfigure to the right ones later? Or some other method I'm not thinking of.

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• How would you gather client's data on Google App Engine without using Datastore/Backend Instances too much?

  - by ruslan

  I'm relatively new to StackExchange and not sure if it's appropriate place to ask design question. Site gives me a hint "The question you're asking appears subjective and is likely to be closed". Please let me know. Anyway.. One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting? Thank you very much in advance for your thoughts.

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• How to stop a Linux LVM volume group?

  - by thkala

  I am currently dealing with a multiple disk failure on a Linux LVM Volume Group that is backed up by a RAID-5 md device. One disk has been taken out completely and another one is showing a limited number of corrupt sectors, due to what seems to have been a misbehaving power supply. The problem is that once an I/O error hits, md takes the array down, since it does not have enough devices for it to be operational. Where md the only one involved, I could mdadm --stop the array and then recreate it to get all devices active again. Unfortunately, the array is a PV in an LVM volume group and I cannot seem to get the kernel to release it. vgchange -an does not seem to do anything, bar spew out a couple of I/O errors. I am obviously missing something, but how in the name of -insert-favorite-deity- do I get LVM to release the underlying PV without rebooting the server?

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• Controlling a GameObject from another GameObject's script component

  - by OhMrBigshot

  I'm creating a game where when starting the game, a Cube is duplicated GridSize * GridSize times when the game starts. Now, after the cubes are duplicated I want to attach a variable to them, say "Flag" which is a bool, from another script component (let's say I have a Prefab that generates the cloned cubes). In short, I have something like this: CreateTiles.cs : Attached to Prefab void Start() { createMyTiles(); // a function that clones the tiles flagRandomTiles(); // a function that (what I'm trying to do) "Flags" 10 random cubes } CubeBehavior.cs : Attached to each Cube public bool hasFlag; // other stuff Now, I want flagRandomTiles() to set a Cube's hasFlag property via code, assuming I have access to them via a GameObject[] array. Here's what I've tried: Cubes[x].hasFlag = true; - No access. Making a function such as Cubes[x].setHasFlag(true) - still no access. Initializing Cubes as a CubeBehavior object array, then doing the above - GameObjects can't be converted to CubeBehaviors - I get this error when I try to assign the Cubes into the array. How do I do this?

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• Dividing up spritesheet in Javascript

  - by hustlerinc

  I would like to implement an object for my spritesheets in Javascript. I'm very new to this language and game-developement so I dont really know how to do it. My guess is I set spritesize to 16, use that to divide as many times as it fits on the spritesheet and store this value as "spritesheet". Then a for(i=0;i<spritesheet.length;i++) loop running over the coordinates. Then tile = new Image(); and tile.src = spritesheet[i] to store the individual sprites based on their coordinates on the spritesheet. My problem is how could I loop trough the spritesheet and make an array of that? The result should be similar to: var tile = Array( "img/ground.png", "img/crate.png" ); If possible this would be done with one single object that i only access once, and the tile array would be stored for later reference. I couldn't find anything similar searching for "javascript spritesheet". Edit: I made a small prototype of what I'm after: function Sprite(){ this.size = 16; this.spritesheet = new Image(); this.spritesheet.src = 'img/spritesheet.png'; this.countX = this.spritesheet.width / 16; this.countY = this.spritesheet.height / 16; this.spriteCount = this.countX * this.countY; this.divide = function(){ for(i=0;i<this.spriteCount;i++){ // define spritesheet coordinates and store as tile[i] } } } Am I on the right track?

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• Design guideline for saving big byte stream in c# [migrated]

  - by Praveen

  I have an application where I am receiving big byte array very fast around per 50 miliseconds. The byte array contains some information like file name etc. The data (byte array ) may come from several sources. Each time I receive the data, I have to find the file name and save the data to that file name. I need some guide lines to how should I design it so that it works efficient. Following is my code... public class DataSaver { private static Dictionary<string, FileStream> _dictFileStream; public static void SaveData(byte[] byteArray) { string fileName = GetFileNameFromArray(byteArray); FileStream fs = GetFileStream(fileName); fs.Write(byteArray, 0, byteArray.Length); } private static FileStream GetFileStream(string fileName) { FileStream fs; bool hasStream = _dictFileStream.TryGetValue(fileName, out fs); if (!hasStream) { fs = new FileStream(fileName, FileMode.Append); _dictFileStream.Add(fileName, fs); } return fs; } public static void CloseSaver() { foreach (var key in _dictFileStream.Keys) { _dictFileStream[key].Close(); } } } How can I improve this code ? I need to create a thread maybe to do the saving.

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• Processing component pools problem - Entity Subsystem

  - by mani3xis

  Architecture description I'm creating (designing) an entity system and I ran into many problems. I'm trying to keep it Data-Oriented and efficient as much as possible. My components are POD structures (array of bytes to be precise) allocated in homogeneous pools. Each pool has a ComponentDescriptor - it just contains component name, field types and field names. Entity is just a pointer to array of components (where address acts like an entity ID). EntityPrototype contains entity name and array of component names. Finally Subsystem (System or Processor) which works on component pools. Actual problem The problem is that some components dependents on others (Model, Sprite, PhysicalBody, Animation depends on Transform component) which makes a lot of problems when it comes to processing them. For example, lets define some entities using [S]prite, [P]hysicalBody and [H]ealth: Tank: Transform, Sprite, PhysicalBody BgTree: Transform, Sprite House: Transform, Sprite, Health and create 4 Tanks, 5 BgTrees and 2 Houses and my pools will look like: TTTTTTTTTTT // Transform pool SSSSSSSSSSS // Sprite pool PPPP // PhysicalBody pool HH // Health component There is no way to process them using indices. I spend 3 days working on it and I still don't have any ideas. In previous designs TransformComponent was bound to the entity - but it wasn't a good idea. Can you give me some advices how to process them? Or maybe I should change the overall design? Maybe I should create pools of entites (pools of component pools) - but I guess it will be a nightmare for CPU caches. Thanks

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• Upgrading drives on a MD3000

  - by Anonymouse

  Hello, Our MD3000 array is getting full as our databases are growing and we need more spaces. Currently, we use a MD3000 with a two-servers Windows 2003 cluster and 15x 73GB SAS drives. Disk groups are configured in RAID1 of two drives. The approach we are currently investigating is simply swapping the existing SAS drives with bigger ones (300GB instead of 73GB), one at a time, and let each RAID1 array rebuilt. Is it a good approach? Will we be able to resize the array afterwards? Will we be able to resize the partitions afterwards? Can the Dell M3000 Management software do it or will we have to bring the server offline and use some partition software to do it? Thanks in advance.

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• How can I set up FakeRAID/SoftRAID using mdadm without losing data?

  - by Danatela

  There is RAID0 of 2 drives connected through Silicon Image 3132 SATA SoftRAID controller. Under Windows it was partitioned as one dynamic GPT-disk having 4 TB NTFS volume. There is a lot of music and movies on the drive. I'm trying to get him to be seen under Ubuntu as a single disk, not as 2 by 2 terabytes. I tried to read it through dmraid, had no success, it is not displayed in /dev/mapper. Also tried to configure the kernel, but did not find anything suspicious, the driver for my controller was on. There is also a driver from the manufacturer, but it is only available for RHEL and SLES. Here it's reported that SoftRAID is supported by the kernel, but apparently not completely. If I thrust drives in the AMD controller, built into the motherboard, the drive is seen as a single, but the data is lost. I know about mdadm that it is able to ditch all the information on the disks. So, is it possible to somehow create an array without actually recording information on used drives and to make the system correctly identify sections on it later? Information about the array: /dev/sdf - Disk 0 /dev/sdg - Disk 1 Array type: Stripe Block Size: 64KB Also, a device /dev/md1 is created using command mknod /dev/md1 b 9 1

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• How can I gather client's data on Google App Engine without using Datastore/Backend Instances too much?

  - by ruslan

  One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting?

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• Sprite transparency not effected libGDX

  - by Aon GoltzCrank

  I am making a game using libGDX and Tween Universal Engine. My problem is as follows: I have 2 screens so fars, a splash screen with the logo, and a second one which is the main menu. In the splash screen I use a SpriteBatch and a Sprite with the Texture of the image I want (which goes through some scaling.) Now I use the Tween engine, along with a created SpriteAccessor to control the alpha of the sprite. I fade the picture in, then fade it out, then change it to the next screen. In the next screen I have a single sprite, and a single, 3 slot, sprite array. In this screen I also use the tween engine, I fade the single sprite into the screen (it's the background image) then I try to, using the same method, (Tween.to) to change the alpah of the sprite array (each sprite by itself.), I first set it to 0 using Tween.set, then using the method I change it. This didn't work, after some tests I tried setting the alpha of a single sprite from the array to 0, and that didn't work. It's like the program is ignoring the alpha value, I even printed out the alpha value, it saying 0, but the sprite is visible. How can I fix this, or why might it be caused?

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