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• How many users are sufficient to make a heavy load for web application

  - by galymzhan

  I have a web application, which has been suffering high load recent days. The application runs on single server which has 8-core Intel CPU and 4gb of RAM. Software: Drupal 5 (Apache 2, PHP5, MySQL5) running on Debian. After reaching 500 authenticated and 200 anonymous users (simultaneous), the application drastically decreases its performance up to total failure. The biggest load comes from authenticated users, who perform activities, causing insert/update/deletes on db. I think mysql is a bottleneck. Is it normal to slow down on such number of users? EDIT: I forgot to mention that I did some kind of profiling. I runned commands top, htop and they showed me that all memory was being used by MySQL! After some time MySQL starts to perform terribly slow, site goes down, and we have to restart/stop apache to reduce load. Administrators said that there was about 200 active mysql connections at that moment. The worst point is that we need to solve this ASAP, I can't do deep profiling analysis/code refactoring, so I'm considering 2 ways: my tables are MyIsam, I heard they use table-level locking which is very slow, is it right? could I change it to Innodb without worry? what if I take MySQL, and move it to dedicated machine with a lot of RAM?

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• Socket Read In Multi-Threaded Application Returns Zero Bytes or EINTR (-1)

  - by user309670

  Hi. Am a c-coder for a while now - neither a newbie nor an expert. Now, I have a certain daemoned application in C on a PPC Linux. I use PHP's socket_connect as a client to connect to this service locally. The server uses epoll for concurrent connections via a Unix socket. A user submitted string is parsed for certain characters/words using strstr() and if found, spawns 4 joinable threads to different websites simultaneously. I use socket, connect, write and read, to interact with the said webservers via TCP on port 80 in each thread. All connections and writes seems successful. Reads to the webserver sockets fail however, with either (A) all 3 threads seem to hang, and only one thread returns -1 and errno is set to 104. The responding thread takes like 10 minutes - an eternity long:-(. *I read somewhere that the 104 (is EINTR) suggests that ...'the connection was reset by peer', or (B) 0 bytes from 3 threads, and only 1 of the 4 threads actually returns some data. Isn't the socket read/write thread-safe? Otherwise, use thread-safe (and reentrant) libc functions such as strtok_r, gethostbyname_r, etc. *I doubt that the said webhosts are actually resetting the connection, because when I run a single-threaded standalone (everything else equal) all things works perfectly right. There's a second problem too (oops), I can't write back to the client who connect to my epoll-ed Unix socket. My daemon application will hang and hog CPU 100% for ever. Yet nothing is written to the clients end. Am sure the client (a very typical PHP socket application) hasn't closed the connection whenever this is happening - no error(s) detected either. I cannot figure-out whatever is wrong even with Valgrind or GDB

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• Start developing a database application using Oracle + Net Beans

  - by Ranhiru

  I have thought of creating my first database application for one of my projects using Oracle and Java. I have chosen Netbeans as my development environment. I have a few questions to getting started. Please bare with me as I'm a complete beginner to Oracle + Netbeans This will be a data intensive (yet still for a college project) database application. I do not need 1000 user concurrency or any other very advanced features but basic stuff such as triggers, stored procedures etc. Will the 11g "Express" (XE) suffice for my requirements? Do i need any Java to Oracle bridge (database connectivity driver eg. ODBC etc) for Netbeans to connect to the oracle database? If yes, what are they? Does Netbeans support Oracle databases natively? Any easy to follow guide on how do i connect to the database and insert/retrieve/display data on a J2SE application? (I know that i should Google this but if there's any guide previously followed by anyone and is considered easy, it would be greatly appreciated.)

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• How to return output from .Net Dll to the calling Application

  - by sachin

  I have to create one VB.Net Dll for VB.Net Application.In DLL there will be function to calculate the fee based on some parameter which I pass when call the function from appllication, output of calculated fee would be this type **Validations are not selected. Rate information: IN:11/14/20113:12:38 PM; OUT:11/15/20113:12:38 PM; Fee:3; Description:$3 Fixed IN:11/14/20113:12:38 PM; OUT:11/15/20113:12:38 PM; Fee:1; Description:$1 Fixed Sub Total: IN: 11/14/20113:12:38 PM; OUT: 11/15/20113:12:38 PM; Fee:4; Description: Rate Group1 Rate information: IN:11/14/20113:12:38 PM; OUT:11/15/20113:12:38 PM; Fee:3; Description:$3 Fixed Sub Total: IN: 11/14/20113:12:38 PM; OUT: 11/15/20113:12:38 PM; Fee:3; Description: Rate Group1** Can anybody tell me how can I return output of this type to the application ,so that I can use it in that application.

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• Send Click Message to another application process

  - by Nazar Hussain

  I have a scenario, i need to send click events to an independent application. I started that application with the following code. private Process app; app = new Process(); app.StartInfo.FileName = app_path; app.StartInfo.WorkingDirectory = dir_path; app.Start(); Now i want to send Mouse click message to that applicaiton, I have specific coordinates in relative to application window. How can i do it using Windows Messaging or any other technique. I used [DllImport("user32.dll")] private static extern void mouse_event(UInt32 dwFlags, UInt32 dx, UInt32 dy, UInt32 dwData, IntPtr dwExtraInfo); It works well but cause the pointer to move as well. So not fit for my need. Then i use. [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = false)] static extern IntPtr SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam); It works well for minimize maximize, but do not work for mouse events. The codes for mousevents i am using are, WM_LBUTTONDOWN = 0x201, //Left mousebutton down WM_LBUTTONUP = 0x202, //Left mousebutton up WM_LBUTTONDBLCLK = 0x203, //Left mousebutton doubleclick WM_RBUTTONDOWN = 0x204, //Right mousebutton down WM_RBUTTONUP = 0x205, //Right mousebutton up WM_RBUTTONDBLCLK = 0x206, //Right mousebutton do Thanks for the help in advance, and waiting for feedback.

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• The application has stopped unexpectedly: How to Debug?

  - by Android Eve

  Please note, unlike many other questions having the subject title "application has stopped unexpectedly", I am not asking for troubleshooting a particular problem. Rather, I am asking for an outline of the best strategy for an Android/Eclipse/Java rookie to tackle this formidable task of digesting huge amounts of information in order to develop (and debug!) a simple Android application. In my case, I took the sample skeleton app from the SDK, modified it slightly and what did I get the moment I try to run it? The application (process.com.example.android.skeletonapp) has stopped unexpectedly. Please try again. OK, so I know that I have to look LogCat. It's full of timestamped lines staring at me... What do I do now? What do I need to look for? Is there a way to single-step the program, to find the statement that makes the app crash? (I thought Java programs never crash, but apparently I was mistaken) How do I place a breakpoint? Can you recommend an Android debug tutorial online, other than this one?

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• Getting Started: Silverlight 4 Business Application

  - by Eric J.

  With the arrival of VS 2010 and Silverlight 4, I decided it's time to look into Silverlight and understand how to build a 3-Tier business application. After several hours of searching for and reading documentation and tutorials, I'm thoroughly confused (and that doesn't happen easily). Here are some specific points I don't understand. I welcome guidance on any of them, and also would appreciate any references to a really good tutorial. Brad Abrahm's What is a .NET RIA services (written for Silverlight 3) seemed very promising, until I realized I don't have System.Web.Ria.dll on my system. Am I missing an optional download? Was this rolled into another DLL for Silverlight 4? Did this go away in favor of something else in Silverlight 4? This recent blog says to start from a Silverlight Business Application, remove unwanted stuff, create a WCF RIA services Class Library project, and copy files and references from the Business Application to the WCF RIA services project, while manually updating resource references (perhaps bug in B2 compiler). Is this really the right road to go down? It seems very clumsy. My requirements are to perform very simple CRUD on straightforward business objects. I'm looking forward to suggestions on how to do that the Silverlight 4 way.

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• .NET Application with SQL Server CE Database

  - by blu

  I just started using SQL Server CE 3.5 in my WinForms Application (C# in VS 2008 SP1). I've noticed a couple of interesting things I'd like some input on: 1. Copying of sdf file to bin My sdf file is located inside of an Infrastructure project that houses my repository implementations. When the application is first debugged the sdf was copied to debug\bin. This is where all future reads/writes operate. At some point when this is deployed the file will go into a data folder using Click Once, but during development where should I be putting this sdf? Is having it in the bin typical, or are there any other recommendations? 2. Updating sdf It appears that writing to the sdf file does not immediately update the database. I am using Linq-to-SQL and am calling SubmitChanges, but on read the values are not returned. However if I close the application and re-open it the added value is there. Is there an additional flush step I need to take? What is causing this, file locking, buffering, something else? Update 3. Unit Tests I have an MS test project, and the sdf file is not being copied to the correct output directory. I have the settings: Build Action: Content Copy to Output Directory: Copy Always The message is: System.Data.SqlServerCe.SqlCeException: The database file cannot be found. Check the path to the database. I appreciate any guidance on these questions, thanks. If there is a tutorial other than what is on MSDN that you know about that would be great too. Working with CE is proving to be a difficult task and I welcome any help I can find.

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• Detect if any USB drive is detected or not using WinForm Application

  - by Pavan Kumar

  I want to do the following things in my application 1) I want to display whether any USB drive is inserted or not in my application to prompt the user to insert a USB drive. I just want to notify the user if any USB dirve is inserted else prompt him to insert one using a label or something (i want to avoid messagebox as it will keep appearing whenever a device is inserted or removed. It will be irritating for the end user) in my Visual C# WinForm Application. If any USB drive is present display "USB drive detected" in the label. The user may add one or more USB sticks but the status will remain same. When there is none then the status of the label will change to "No USB drives found.Please insert a USB drive". 2) When one or more USB drive is added the volume name with the drive letter for example "James(F:)" is added to the Combobox list. The combobox list also needs to remove the entry for the USB drive added in the list automatically when it is removed . So when there is no USB the list should be empty and the label will again prompt user to insert a USB stick or drive.

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• How an application or website finds your ip?

  - by johnkills

  I think there are only two ways a application or a server could get your IP. If it is an application, java/flash, I think it could check your network settings locally and send your IP back to the server. Then the server would know. The other way it could find is that it could analyze the packet headers. Then find there your IP information. But if I wanted it to stop doing it. If it was analyzing locally my IP information I could stop that packet or change its information so the website would be confused about the IP information. If it was analyzing the packet headers and if knew what packets it was analyzing because it wont analyze every packet, I could stop sending those packets. Example: Websites that checks your IP, how does it do it? If you are not downloading any application, you would exclude the 1. scenarion. Then the only possibility is that it was analyzing packet headers but what kind of packets? It was not one question only but if anyone knows something about it, I would like to know too. :) Thanks

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• iPhone application purchase verification -- possible?

  - by Sedate Alien

  The iPhone 3.0 SDK's StoreKit.framework provides support for in-app purchases to give the user additional content, functionality and so on. It is possible for an app to send the transactionReceipt property of SKPaymentTransaction objects to the developer's server for verification of successful purchasing before granting service. Is there any analogous SDK to verify the initial application purchase itself? A developer that wishes for their server to only provide services to genuine applications (i.e. not pirated) without using IAP could do so by verifying the application in this manner, e.g. ensure that only users with the correct transactionReceipt are catered for. I understand that this approach would still be vulnerable to replay attacks; a dedicated group of pirates could share a valid transactionReceipt. However, my server provides a consumable service to users, i.e. once they've connected and done the work, it needn't work a second time so replay attacks are nullified. The service that my app provides is relatively niche. I could distribute it on the App Store as a free application that requires at least one IAP to do anything useful, but I am lead to believe that this would be a very unpopular move among users as it would be considered misleading. If I distribute it as a paid app, I do not know how to ensure that only genuine apps can access the webservice. This is important as every invocation of the webservice costs me money! What are my options?

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• Setting Icon for wpf application (VS 08)

  - by baron

  Hi everyone, Before going much further i'll mention I have tried solutions in following: http://stackoverflow.com/questions/320677/how-do-i-set-the-icon-for-my-application-in-visual-studio-2008 http://stackoverflow.com/questions/198848/set-application-icon-from-resources-in-vs-05 I am trying to set an icon for my application. AFAIK, I need potentially 3 images? 1 image is the actual image in explorer when clicking on the .exe (thumbnail for the exe) 1 image (tiny) in the top left corner (16 x 16? Not entirely sure) 1 image in the start menu dock, to the left of the app (maybe 32x32? again not sure) So thats fine. Now I have selected an Icon. How do I use it in one of above situations? I have tried adding it in resources, nothing seems to happen. Following that first SO solution, "First go to Resource View (from menu: View -- Other Window -- Resource View). Then in Resource View navigate through resources, if any. If there is already a resource of Icon type, added by Visual Studio, then open and edit it. Otherwise right-click and select Add Resource, and then add a new icon." The resource view is empty, and I cannot right click in this view. If I right click on the solution properties resources I can add the icon image, but it doesn't show in either of the locations listed above. (or anywhere that I can see) What am I doing wrong?

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• How to make a piece of WPF content take up the entire application window

  - by Bojin Li

  I'm working on an application that contains a number of content areas. I want to implement a behavior such that in response to user input, any of these content areas can be toggled to fit the entire application window, and optionally back to its original position again. I experimented with several approaches and none of them seem optimal for me. Here's what I tried to do: Use the ClipToBoundsProperty on the content I want to make "Full Screen": Doesn't work because only the CanvasPanel seems to fully respect this property. The application need to be localized so I would really like to avoid the CanvasPanel. Use a Grid and collapse the other content areas, such that only the one I want to see is visible, hence taking up the entire screen: This will probably work but doesn't seem easy to implement nor maintain. The "Full Screen" content area could be several levels deep, for example residing inside a Tabcontrol, so I would have to hide the tab headers too etc. Reconstruct the content area in a separate view and display it while hiding the rest: Seems easy enough to do with DataTemplates and my ViewModel objects, but any GUI/View only states are not preserved using this approach. Somehow "lift" the GUI/View I want to "Full Screen" into the separate view and display it while hiding the rest: I don't know how to do this or even if this is possible. Anyway if anyone knows a better approach I would love to know about it. Thanks a lot!

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• Data Application based on OO Concepts

  - by The King

  Hi... I'm looking for an application developed in C# with following qualities, which is available as source code... Based on OO Architecture Must connect to DB. Must handle atleast a "one to many master child" relationship (eg: Order and items ordered) Should display the data using Datagrid or other similar controls. Reports (either with report buider or otherwise) I want to understand the layering of objects better... Do you have any links... Thanks.

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• Window Application

  - by user350104

  how to create connection using class file in C# for windows application?... how to develop Data access layer... regarding 3-tire architecture using mysql databases

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• PyQt4 plugin in c++ application

  - by veverica17

  How is it posible to load python script as plugin in qt based application? The basic idea would be to make a class in c++ class b { virtual void method1(); virtual void method2(); } and 'somehow' inherit it in python like class c(b): def method1: #do something def method2: #do something I need to be able to modify the gui from python( add buttons to some widgets made in c++ with qt ). Basicaly something similiar to (gedit, blender, etc) plugin architecture with qt

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• What's a good approach to adding debug code to your application when you want more info about what's going wrong?

  - by Andrei

  When our application doesn't work the way we expect it to (e.g. throws exceptions etc.), I usually insert a lot of debug code at certain points in the application in order to get a better overview of what exactly is going on, what the values for certain objects are, to better trace where this error is triggered from. Then I send a new installer to the user(s) that are having the problem and if the problem is triggered again I look at the logs and see what they say. But I don't want all this debug code to be in the production code, since this would create some really big debug files with information that is not always relevant. The other problem is that our code base changes, and the next time, the same debug code might have to go in different parts of the application. Questions Is there a way to merge this debug code within the production code only when needed and have it appear at the correct points within the application? Can it be done with a version control system like git so that all would be needed is a git merge? P.S. The application I'm talking about now is .NET, written in C#.

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• Where can I find the application executables in the filesystem?

  - by richzilla

  Where are executables for programs stored in Ubuntu? An application (Komodo Edit) is asking me to identify an application to be used as a web browser. I've become used to just entering the application name as a command for situations such as these, but this scenario got me thinking. I know in Windows it would just be the relevant application folder in the 'program files' folder, but I'm assuming things are a bit different on Linux? I thought somewhere like bin would be logical but this appears to standard Linux/Unix applications. Where would I find the binary executable for applications stored on my system?

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• Evolution of an Application: how to manage and improve core engine?

  - by Phil Carter

  The web application I work on has been live for a year now, but it's time for it to evolve and one of the ways in which it is evolving is into a multi-brand application - in this case several different companies using the application, different templates/content and some slight business logic changes between them. The problem I'm facing is implementing a best practice across the site where there are differences in business logic for each brand. These will mostly be very superficial, using a an alternative mailing list provider or capturing some extra data in a form. I don't want to have if(brand === x) { ... } else { ... } all over the site especially as most of what needs to be changed can be handled with extending the existing class. I've thought of several methods that could be used to instantiate the correct class, but I'm just not sure which is going to be best especially as some seem to lead to duplication of more code than should be necessary. Here's what I've considered: 1) Use a Static Loader similar to Zend_Loader which can take the class being requested, and has knowledge of the Brand and can then return the correct object. $class = App_Loader::getObject('User', $brand); 2) Factory classes. We use these in the application already for Products but we could utilise them here also to provide a transparent interface to the class. 3) Routing the page request to a specific brand controller. This however seems like it would duplicate a lot of code/logic. Is there a pattern or something else I should be considering to solve this problem? 4) How to manage a growing project that has multiple custom instances in production? Update This is a PHP application so the decisions on which class to load are made per request. There could be upwards of 100+ different 'brands' running.

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• How do I install Cacti 8.7i with PIA 3.1(Plug In Architecture) for 12.04 Server LTS?

  - by Pininy

  I am planning to upgrade my current 9.04 server version to 12.04LTS server. I've successfully backup and restore my Cacti version 8.7d to 8.7i that comes with the distribution. However, the plugin patch installation for PIA 3.1 it is not working for only ubuntu. Can you assist? or it's there a way to include Cacti 8.8a which is a stable version which comes with PIA 3.1 preinstalled. regards, thomas

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• Is there a difference between installing an application via Ubuntu Software Center or a terminal?

  - by gabriel

  I would like to ask a very basic question but I have never thought about it before. Well, when someone installs an application from terminal, he has to add the repository first, right? On the other side, when someone installs an application from the Ubuntu Software Center, is the repository then added automatically? I am asking those questions to figure out this: When I run update and then upgrade, will this application be upgraded or not? Is the result same in two options?

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• WPF and Composite Application Library &ndash; Missing The Point

  - by David Totzke

  I have a headache and it’s not even 9AM yet.  Well, ok, it’s nearly ten here now in GMT –5 but it’s before nine somewhere still. Sometimes people will miss the point of something so utterly and completely that one is left wondering how such a person can even dress themselves. Writing an application using WPF and the Composite Application Library (Prism) means that one must learn the various programming idioms common to these frameworks.  The Windows Forms event driven model simply will not suffice.  You need to come to grips with the idea of a very loosely coupled application.  Concepts that must be absorbed and internalized include Data Binding, Control and Data Templates, Commands, Dependency Injection, and Inversion of Control, as well as the Supervising Controller, Presentation Model and Model-View-View-Model patterns. It is as simple as that.  Not to embrace these concepts is to invite pain.  It is to invite noodles; and not the holy kind. Someone actually said to me that “just because it’s not WPF, doesn’t mean it’s wrong.”  And he’s right.  Unless, of course, you are writing a WPF application and especially if you are using the Composite Application Library. In simple terms then; YOU’RE DOING IT WRONG!   Dave Just because I can…

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• In the future, when mobile devices are embedded in your body, what kind of APIs might be availbe to an application developer?

  - by Conor

  Mobile devices have APIs that allow an application to send and receive SMS, make a phone call, determine location etc. In the future, when mobile devices are embedded in your body, what kind of APIs might be availbe to an application developer? EDIT: This is not intended to be a joke question (but what's the harm in some funny answers?). It's to spur a discussion on how one aspect of mobile device application could pan out and what kind of application might be available. For example: health monitoring - various APIs available to get body temperature, sugar levels, etc for transmission to your GP.

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• Architecture Standards &ndash; BPMN vs. BPEL for Business Process Management

  - by pat.shepherd

  I get asked often which business process standard an organization should use; BPMN or BPEL?  As I explain to folks, they both have strengths.  Here is a great article that helps understand the benefits of both and where to use them.  The good news is that, with Oracle SOA Suite and BPM suite, you have the option and flexibility to use both in the same SCA model and runtime container.  Good stuff. Here is the great article that Mark Nelson wrote: The right tool for the right job BPEL and BPMN are both ‘languages’ or ‘notations’ for describing and executing business processes. Both are open standards. Most business process engines will support one or the other of these languages. Oracle however has chosen to support both and treat them as equals. This means that you have the freedom to choose which language to use on a process by process basis. And you can freely mix and match, even within a single composite. (A composite is the deployment unit in an SCA environment.) So why support both? Well it turns out that BPEL is really well suited to modeling some kinds of processes and BPMN is really well suited to modeling other kinds of processes. Of course there is a pretty significant overlap where either will do a great job What BPM adds to SOA Suite | RedStack

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 6

  - by MarkPearl

  Learning Outcomes Discuss the physical characteristics of magnetic disks Describe how data is organized and accessed on a magnetic disk Discuss the parameters that play a role in the performance of magnetic disks Describe different optical memory devices Magnetic Disk The way data is stored on and retried from magnetic disks Data is recorded on and later retrieved form the disk via a conducting coil named the head (in many systems there are two heads) The writ mechanism exploits the fact that electricity flowing through a coil produces a magnetic field. Electric pulses are sent to the write head, and the resulting magnetic patterns are recorded on the surface below with different patterns for positive and negative currents The physical characteristics of a magnetic disk   Summarize from book   The factors that play a role in the performance of a disk Seek time – the time it takes to position the head at the track Rotational delay / latency – the time it takes for the beginning of the sector to reach the head Access time – the sum of the seek time and rotational delay Transfer time – the time it takes to transfer data RAID The rate of improvement in secondary storage performance has been considerably less than the rate for processors and main memory. Thus secondary storage has become a bit of a bottleneck. RAID works on the concept that if one disk can be pushed so far, additional gains in performance are to be had by using multiple parallel components. Points to note about RAID… RAID is a set of physical disk drives viewed by the operating system as a single logical drive Data is distributed across the physical drives of an array in a scheme known as striping Redundant disk capacity is used to store parity information, which guarantees data recoverability in case of a disk failure (not supported by RAID 0 or RAID 1) Interesting to note that the increase in the number of drives, increases the probability of failure. To compensate for this decreased reliability RAID makes use of stored parity information that enables the recovery of data lost due to a disk failure.   The RAID scheme consists of 7 levels…   Category Level Description Disks Required Data Availability Large I/O Data Transfer Capacity Small I/O Request Rate Striping 0 Non Redundant N Lower than single disk Very high Very high for both read and write Mirroring 1 Mirrored 2N Higher than RAID 2 – 5 but lower than RAID 6 Higher than single disk Up to twice that of a signle disk for read Parallel Access 2 Redundant via Hamming Code N + m Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Parallel Access 3 Bit interleaved parity N + 1 Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Independent Access 4 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, significantly lower than single disk for write Similar to RAID 0 for read, significantly lower than single disk for write Independent Access 5 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, lower than single disk for write Similar to RAID 0 for read, generally  lower than single disk for write Independent Access 6 Block interleaved parity N + 2 Highest of all listed alternatives Similar to RAID 0 for read; lower than RAID 5 for write Similar to RAID 0 for read, significantly lower than RAID 5  for write   Read page 215 – 221 for detailed explanation on RAID levels Optical Memory There are a variety of optical-disk systems available. Read through the table on page 222 – 223 Some of the devices include… CD CD-ROM CD-R CD-RW DVD DVD-R DVD-RW Blue-Ray DVD Magnetic Tape Most modern systems use serial recording – data is lade out as a sequence of bits along each track. The typical recording used in serial is referred to as serpentine recording. In this technique when data is being recorded, the first set of bits is recorded along the whole length of the tape. When the end of the tape is reached the heads are repostioned to record a new track, and the tape is again recorded on its whole length, this time in the opposite direction. That process continued back and forth until the tape is full. To increase speed, the read-write head is capable of reading and writing a number of adjacent tracks simultaneously. Data is still recorded serially along individual tracks, but blocks in sequence are stored on adjacent tracks as suggested. A tape drive is a sequential access device. Magnetic tape was the first kind of secondary memory. It is still widely used as the lowest-cost, slowest speed member of the memory hierarchy.

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