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  • Raidz in FreeNAS eating more space than expected

    - by swood
    I just got 6 new 2TB drives, and added them to my FreeNAS box. I have only dealt with RAID1 previously, and each setup has given what I was expecting. However, with the 6*2TB drives, I wanted to maximize the space available, so I went with raidz. But I seem to be missing space. I have 8.6TB available after the raidz was built. Maybe I did my math horribly wrong, but (N-1) x S(min) (where N=6 and S(min)=2TB) should result in 10TB. (I understand it would be more like 9.something) Does raidz actually consume more then 1 drive worth of space? Or could their possibly be another problem? (All drives have been independently verified that 2TB of space is available)

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  • Install Windows 8 (clean) on Hybrid Drive

    - by Ananthakrishnan Ravi
    I have a Sony Vaio T series (UEFI) that consists of a Hybrid Drive (SSD + HDD). I would like to install Windows 8 on the SSD and keep the Program files and other applications on the hard disk. What I could perceive was to keep the SSD as the System Drive. I'm able to install the OS on the SSD, but I run into some issues where I don't see the Microsoft Store App on my system and there are no apps on Windows 8. I tried using this blog post but doesn't seem to fit for Windows 8. Any help in this regard would be great. I would like the Windows 8 alone on the SSD, I don't care about the space wasted on the SSD and install other programs on my HDD. Thanks

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  • SAN for Medium Business - Where to start? [closed]

    - by Henson
    I've always run Linux on my home computers, and done PC repair for years, but this is my first experience with needing to buy a SAN. I thought I was knowledgeable, but I feel a bit lost. I need to be able to support 25 VMs, which are currently managed through vSphere. The company I'm at is growing quickly though, so I'd like to plan for the future. Ideally, I want a solution that I can just tack arrays onto and manage as one large, iSCSI drive. Suggestions? Good resources? If I can find something that appears to software as one large drive, am I better off going with a solution like FreeNAS or Starwind, or an all-in-one proprietary solution like NetApp? Cost, is (of course, and always I'm sure) an issue.

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  • Server Design Enquiry [closed]

    - by Brandon Gelfand
    I am really new to this and am having trouble with how I can store information from a website. I am going to be making a site similar to dropbox for my company and there is gonna be around 40 TB of space that we need to be able to access on the go, for instance pull the file up on the phone or off our laptop using the internet. Obviously using an Amazon S3 server is not the most cost effective way of doing this so how can I make my own server to hold all of the info and communicate to it from a website? Please I need as much help as possible, like a blueprint or something. Thanks and sorry for the noobish question but I can't really find an exact answer to my question.

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  • Restoring a backup SQL Server 2005 where is the data stored?

    - by sc_ray
    I have two Sql Server database instances on two different machines across the network. Lets call these servers A and B. Due to some infrastructural issues, I had to make a complete backup of the database on server A and robocopy the A.bak over to a shared drive accessible by both A and B. What I want is to restore the database on B. My first issue is to restore the backup on server B but the backup location does not display my shared drive. My next issue is that server B's C: drive has barely any space left and there are some additional partitions that have more space and can house my backup file but I am not sure what happens to the data after I restore the database on B. Would the backup data fill up all the available space on C:? It will be great if somebody explain how the data is laid out after the restore database is initiated on a target database server? Thanks

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  • Cloud Agnostic Architecture?

    - by Dave
    Hi, I'm doing some architecture work on a new solution which will initially run in Windows Azure. However I'd like the solution (or at least the architecture/design) to be Cloud Agnostic (to whatever extent is realistic). Has anyone done any work on this front or seen any good white papers/blog posts? Our highlevel architecture will consist of a payload being sent to a web service (WCF for instance), this will be dumped on a queue (for arguments sake) and a worker process will grab messages off this queue and proccess them. There will be a database of customer information which we'd ideally like to keep out of the cloud however there are obvious performance considerations. Keen to hear other's thoughts. Cheers Dave

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  • Problem in displaying the movie file in silverlight

    - by BALAMURUGAN
    I am developing a portal for online theatre system. I will show the movie in online website daily in shows(like 6-10 PM Shows). I am using Silverlight to display the video in web application. I am holding my movie file in Windows Azure Blob. I am having a problem displaying the movie file. Consider if ay user login to web system @6 The movie will show from starting.. If the user login to the system @7 the movie should start whats going now in the screen for other user not from the begining of the movie. How can I achieve tis.

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  • Compressing as GZip WCF requests (SOAP and REST)

    - by Joannes Vermorel
    I have a .NET 3.5 web app hosted on Windows Azure that exposes several WCF endpoints (both SOAP and REST). The endpoints typically receive 100x more data than they serve (lot of data is upload, much fewer is downloaded). Hence, I am willing to take advantage from HTTP GZip compression but not from the server viewpoint, but rather from the client viewpoint, sending compressed requests (returning compressed responses would be fine, but won't bring much gain anyway). Here is the little C# snippet used on the client side to activate WCF: var binding = new BasicHttpBinding(); var address = new EndpointAddress(endPoint); _factory = new ChannelFactory<IMyApi>(binding, address); _channel = _factory.CreateChannel(); Any idea how to adjust the behavior so that compressed HTTP requests can be made?

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  • Can Parallel.ForEach be used safely with CloudTableQuery

    - by knightpfhor
    I have a reasonable number of records in an Azure Table that I'm attempting to do some one time data encryption on. I thought that I could speed things up by using a Parallel.ForEach. Also because there are more than 1K records and I don't want to mess around with continuation tokens myself I'm using a CloudTableQuery to get my enumerator. My problem is that some of my records have been double encrypted and I realised that I'm not sure how thread safe the enumerator returned by CloudTableQuery.Execute() is. Has anyone else out there had any experience with this combination?

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  • Is a Service Bus a good option to communicate with multiple external servers?

    - by PFreitas
    We are developing an application that communicates, via web services or TCP/IP sockets, with multiple servers (up to 50 different external companies). Basically, the exchanged messages are the same (XML), but depending on the inputs of our application we should call 1 or more external servers. The benefits we would expect of introducing a Service Bus in the architecture would be: 1- Remove the need to manage all point-to-point configurations (all the 50 endpoints); 2- Simplify the communication layer of our application by having only one server to talk to; Is a Service Bus a good architectural option for this scenario? What is the best (simplest) Service Bus for this kind of communication? I read a few MSDN articles on Azure Service Bus Relay, but it didn’t seem to fit our needs. Am I wrong? Thanks for your help.

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  • How to cache and store objects and set an expire policy in android?

    - by virsir
    I have an app fetch data from internet, for better performance and bandwidth, I need to implement a cache layer. There are two different data coming from the internet, one is changing every one hour and another one does not change basically. So for the first type of data, I need to implement an expire policy to make it self deleted after it was created for 1 hour, and when user request that data, I will check the storage first and then goto internet if nothing found. I thought about using a SharedPrefrence or SQLDatabase to store the json data or serialized object string. My question is: 1) What should I use, SharedPrefrence or SQLDatabase or anything else, a piece of data is not big but there are maybe many instances of that data. 2) How to implement that expire system.

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  • Best way to store data for Greasemonkey based crawler?

    - by Björn
    I want to crawl a site with Greasemonkey and wonder if there is a better way to temporarily store values than with GM_setValue. What I want to do is crawl my contacts in a social network and extract the Twitter URLs from their profile pages. My current plan is to open each profile in it's own tab, so that it looks more like a normal browsing person (ie css, scrits and images will be loaded by the browser). Then store the Twitter URL with GM_setValue. Once all profile pages have been crawled, create a page using the stored values. I am not so happy with the storage option, though. Maybe there is a better way? I have considered inserting the user profiles into the current page so that I could all process them with the same script instance, but I am not sure if XMLHttpRequest looks indistignuishable from normal user initiated requests.

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  • How do I use Amazon's new RRS for S3?

    - by pbarney
    Reduced Redundancy Storage (RRS) is a new service from Amazon that is a bit cheaper than S3 because there is less redundancy. However, I can not find any information on how to specify that my data should use RRS rather than standard S3. In fact, there doesn't seem to be any website interface for an S3 services. If I log into AWS, there are only options for EC2, Elastic MapReduce, CloudFront and RDS, none of which I use. Any insight? Thanks.

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  • CMS for SmartPhones

    - by dde
    The company I work for has a document management and retrieval system. We are noticing employees use more their smartphones than their laptops, but they cannot access the document management system. So, we are thinking about a CMS, with persistent storage, perhaps developed in Java. I just started looking into Jease and dotCMS, and also checked here those recommendations in questions like "Best Open Source Java CMS", etc I find some CMSs too bulky for simple stuff like what we need which is basically document download/edit/upload, and some simple collaboration and personalization stuff. Smartphones of choice in our workforce are Nokia, Blackberry and IPhone, The question is: are there java based with persistent db CMSs aimed at Smartphones right now? I need replication of the complete database and run website offline.

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  • Multiple storages using localStorage

    - by Blondie
    Hey, Is it possible that the same name used can have many different values stored separately and to be shown in a list? e.g. function save() { var inputfield = document.getElementById('field').innerHTML; localStorage['justified'] = inputfield; } <input type="text" id="field" onclick="save();" /> Everytime someone enters something in the input field, and click on save, the localstorage will only save the value in the same name, however, does this conflict the way storage are saved, like being replaced with the latest input value? Also, is there anyway to prevent clearing the localstorage when clearing the cache? Thanks.

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  • Do bit operations cause programs to run slower?

    - by flashnik
    I'm dealing with a problem which needs to work with a lot of data. Currently its values are represented as an unsigned int. I know that real values do not exceed a limit of 1000. Questions I can use unsigned short to store it. An upside to this is that it'll use less storage space to store the value. Will performance suffer? If I decided to store data as short but all the calling functions use int, it's recognized that I need to convert between these datatypes when storing or extracting values. Will performance suffer? Will the loss in performance be dramatic? If I decided to not use short but just 10 bits packed into an array of unsigned int. What will happen in this case comparing with previous ones?

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  • What open source document-oriented database system is most mature for Windows usage?

    - by jdk
    After using relational databases as back-end storage all my Windows programming life (currently .NET), I want to experiment with a document-oriented database by this Wikipedia definition; it can be standalone or layered over an existing non-commercial database system. What open source document-oriented database solution would you recommend from your own experience and why? A nice to have would be a .NET provider. Admittedly this is somewhat subjective and potentially argumentative so keep it real folks and I'll do the same - also your answers will be invaluable to others looking into document-oriented databases for the first time on Windows. I'm sure the overall value of your answers will outweigh any biases. Thanks.

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  • Sorting array of 1000 distinct integers in the range [1, 5000], accessing each element at most once

    - by Cronydevil
    Suppose you have an array of 1000 integers. The integers are in random order, but you know each of the integers is between 1 and 5000 (inclusive). In addition, each number appears only once in the array. Assume that you can access each element of the array only once. Describe an algorithm to sort it. How i can sorting? If you used auxiliary storage in your algorithm, can you find an algorithm that remains O(n) space complexity?

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  • Storing data with a stand-alone C++ application

    - by Mike
    I work with Apache, PHP, and MySQL for web development and local applications. For the past couple of years I have slowly been learning C++ and want to build an application this summer. Specifically, I want to make a "library" application in which I can store information about the books, CDs, and records that I own. I know this type of app exists, but I want to learn C++ and this seems like a good way to go about it. Here are a few questions: Is it possible to create a stand-alone application that does not require a database for storing data? If the answer to #1 above is "yes", is it a good idea to do this for an application that could potentially need to manage a lot of data? What data-storage options would you recommend for use with a C++ application? Thanks!

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  • Are there any portable Cloud APIs that allow you to easily change cloud hosts?

    - by MindJuice
    I am creating a web-based RESTful service and want to cloud-enable it for scalability. I don't want to get locked into one cloud provider though. I'd like to be able to switched between Go Grid or Amazon EC2, etc. as pricing and needs evolve. Is there a common API to control the launch, monitoring and shutdown of cloud resources? I've seen Right Scale, but their pricing is just from another planet. Similarly, is there a common API for cloud storage?

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  • An efficient way to store view counts for objects?

    - by Nick Brooks
    I maintain an application where users are able to store images, and then share them. The system is powered by MongoDB at the back end. Most of the image depiction pages are cached as flat HTML files, but I can run some code just before loading the file. I've decided to implement a view count for the system. I am wondering what is the best storage place for that. It should be like Memcached but it should save the viewcounts every hour or so, so even if our server has to be restarted we won't lose the view counts. What is the best solution for that (preferably with a PHP extension as a client)?

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  • Node.js Adventure - When Node Flying in Wind

    - by Shaun
    In the first post of this series I mentioned some popular modules in the community, such as underscore, async, etc.. I also listed a module named “Wind (zh-CN)”, which is created by one of my friend, Jeff Zhao (zh-CN). Now I would like to use a separated post to introduce this module since I feel it brings a new async programming style in not only Node.js but JavaScript world. If you know or heard about the new feature in C# 5.0 called “async and await”, or you learnt F#, you will find the “Wind” brings the similar async programming experience in JavaScript. By using “Wind”, we can write async code that looks like the sync code. The callbacks, async stats and exceptions will be handled by “Wind” automatically and transparently.   What’s the Problem: Dense “Callback” Phobia Let’s firstly back to my second post in this series. As I mentioned in that post, when we wanted to read some records from SQL Server we need to open the database connection, and then execute the query. In Node.js all IO operation are designed as async callback pattern which means when the operation was done, it will invoke a function which was taken from the last parameter. For example the database connection opening code would be like this. 1: sql.open(connectionString, function(error, conn) { 2: if(error) { 3: // some error handling code 4: } 5: else { 6: // connection opened successfully 7: } 8: }); And then if we need to query the database the code would be like this. It nested in the previous function. 1: sql.open(connectionString, function(error, conn) { 2: if(error) { 3: // some error handling code 4: } 5: else { 6: // connection opened successfully 7: conn.queryRaw(command, function(error, results) { 8: if(error) { 9: // failed to execute this command 10: } 11: else { 12: // records retrieved successfully 13: } 14: }; 15: } 16: }); Assuming if we need to copy some data from this database to another then we need to open another connection and execute the command within the function under the query function. 1: sql.open(connectionString, function(error, conn) { 2: if(error) { 3: // some error handling code 4: } 5: else { 6: // connection opened successfully 7: conn.queryRaw(command, function(error, results) { 8: if(error) { 9: // failed to execute this command 10: } 11: else { 12: // records retrieved successfully 13: target.open(targetConnectionString, function(error, t_conn) { 14: if(error) { 15: // connect failed 16: } 17: else { 18: t_conn.queryRaw(copy_command, function(error, results) { 19: if(error) { 20: // copy failed 21: } 22: else { 23: // and then, what do you want to do now... 24: } 25: }; 26: } 27: }; 28: } 29: }; 30: } 31: }); This is just an example. In the real project the logic would be more complicated. This means our application might be messed up and the business process will be fragged by many callback functions. I would like call this “Dense Callback Phobia”. This might be a challenge how to make code straightforward and easy to read, something like below. 1: try 2: { 3: // open source connection 4: var s_conn = sqlConnect(s_connectionString); 5: // retrieve data 6: var results = sqlExecuteCommand(s_conn, s_command); 7: 8: // open target connection 9: var t_conn = sqlConnect(t_connectionString); 10: // prepare the copy command 11: var t_command = getCopyCommand(results); 12: // execute the copy command 13: sqlExecuteCommand(s_conn, t_command); 14: } 15: catch (ex) 16: { 17: // error handling 18: }   What’s the Problem: Sync-styled Async Programming Similar as the previous problem, the callback-styled async programming model makes the upcoming operation as a part of the current operation, and mixed with the error handling code. So it’s very hard to understand what on earth this code will do. And since Node.js utilizes non-blocking IO mode, we cannot invoke those operations one by one, as they will be executed concurrently. For example, in this post when I tried to copy the records from Windows Azure SQL Database (a.k.a. WASD) to Windows Azure Table Storage, if I just insert the data into table storage one by one and then print the “Finished” message, I will see the message shown before the data had been copied. This is because all operations were executed at the same time. In order to make the copy operation and print operation executed synchronously I introduced a module named “async” and the code was changed as below. 1: async.forEach(results.rows, 2: function (row, callback) { 3: var resource = { 4: "PartitionKey": row[1], 5: "RowKey": row[0], 6: "Value": row[2] 7: }; 8: client.insertEntity(tableName, resource, function (error) { 9: if (error) { 10: callback(error); 11: } 12: else { 13: console.log("entity inserted."); 14: callback(null); 15: } 16: }); 17: }, 18: function (error) { 19: if (error) { 20: error["target"] = "insertEntity"; 21: res.send(500, error); 22: } 23: else { 24: console.log("all done."); 25: res.send(200, "Done!"); 26: } 27: }); It ensured that the “Finished” message will be printed when all table entities had been inserted. But it cannot promise that the records will be inserted in sequence. It might be another challenge to make the code looks like in sync-style? 1: try 2: { 3: forEach(row in rows) { 4: var entity = { /* ... */ }; 5: tableClient.insert(tableName, entity); 6: } 7:  8: console.log("Finished"); 9: } 10: catch (ex) { 11: console.log(ex); 12: }   How “Wind” Helps “Wind” is a JavaScript library which provides the control flow with plain JavaScript for asynchronous programming (and more) without additional pre-compiling steps. It’s available in NPM so that we can install it through “npm install wind”. Now let’s create a very simple Node.js application as the example. This application will take some website URLs from the command arguments and tried to retrieve the body length and print them in console. Then at the end print “Finish”. I’m going to use “request” module to make the HTTP call simple so I also need to install by the command “npm install request”. The code would be like this. 1: var request = require("request"); 2:  3: // get the urls from arguments, the first two arguments are `node.exe` and `fetch.js` 4: var args = process.argv.splice(2); 5:  6: // main function 7: var main = function() { 8: for(var i = 0; i < args.length; i++) { 9: // get the url 10: var url = args[i]; 11: // send the http request and try to get the response and body 12: request(url, function(error, response, body) { 13: if(!error && response.statusCode == 200) { 14: // log the url and the body length 15: console.log( 16: "%s: %d.", 17: response.request.uri.href, 18: body.length); 19: } 20: else { 21: // log error 22: console.log(error); 23: } 24: }); 25: } 26: 27: // finished 28: console.log("Finished"); 29: }; 30:  31: // execute the main function 32: main(); Let’s execute this application. (I made them in multi-lines for better reading.) 1: node fetch.js 2: "http://www.igt.com/us-en.aspx" 3: "http://www.igt.com/us-en/games.aspx" 4: "http://www.igt.com/us-en/cabinets.aspx" 5: "http://www.igt.com/us-en/systems.aspx" 6: "http://www.igt.com/us-en/interactive.aspx" 7: "http://www.igt.com/us-en/social-gaming.aspx" 8: "http://www.igt.com/support.aspx" Below is the output. As you can see the finish message was printed at the beginning, and the pages’ length retrieved in a different order than we specified. This is because in this code the request command, console logging command are executed asynchronously and concurrently. Now let’s introduce “Wind” to make them executed in order, which means it will request the websites one by one, and print the message at the end.   First of all we need to import the “Wind” package and make sure the there’s only one global variant named “Wind”, and ensure it’s “Wind” instead of “wind”. 1: var Wind = require("wind");   Next, we need to tell “Wind” which code will be executed asynchronously so that “Wind” can control the execution process. In this case the “request” operation executed asynchronously so we will create a “Task” by using a build-in helps function in “Wind” named Wind.Async.Task.create. 1: var requestBodyLengthAsync = function(url) { 2: return Wind.Async.Task.create(function(t) { 3: request(url, function(error, response, body) { 4: if(error || response.statusCode != 200) { 5: t.complete("failure", error); 6: } 7: else { 8: var data = 9: { 10: uri: response.request.uri.href, 11: length: body.length 12: }; 13: t.complete("success", data); 14: } 15: }); 16: }); 17: }; The code above created a “Task” from the original request calling code. In “Wind” a “Task” means an operation will be finished in some time in the future. A “Task” can be started by invoke its start() method, but no one knows when it actually will be finished. The Wind.Async.Task.create helped us to create a task. The only parameter is a function where we can put the actual operation in, and then notify the task object it’s finished successfully or failed by using the complete() method. In the code above I invoked the request method. If it retrieved the response successfully I set the status of this task as “success” with the URL and body length. If it failed I set this task as “failure” and pass the error out.   Next, we will change the main() function. In “Wind” if we want a function can be controlled by Wind we need to mark it as “async”. This should be done by using the code below. 1: var main = eval(Wind.compile("async", function() { 2: })); When the application is running, Wind will detect “eval(Wind.compile(“async”, function” and generate an anonymous code from the body of this original function. Then the application will run the anonymous code instead of the original one. In our example the main function will be like this. 1: var main = eval(Wind.compile("async", function() { 2: for(var i = 0; i < args.length; i++) { 3: try 4: { 5: var result = $await(requestBodyLengthAsync(args[i])); 6: console.log( 7: "%s: %d.", 8: result.uri, 9: result.length); 10: } 11: catch (ex) { 12: console.log(ex); 13: } 14: } 15: 16: console.log("Finished"); 17: })); As you can see, when I tried to request the URL I use a new command named “$await”. It tells Wind, the operation next to $await will be executed asynchronously, and the main thread should be paused until it finished (or failed). So in this case, my application will be pause when the first response was received, and then print its body length, then try the next one. At the end, print the finish message.   Finally, execute the main function. The full code would be like this. 1: var request = require("request"); 2: var Wind = require("wind"); 3:  4: var args = process.argv.splice(2); 5:  6: var requestBodyLengthAsync = function(url) { 7: return Wind.Async.Task.create(function(t) { 8: request(url, function(error, response, body) { 9: if(error || response.statusCode != 200) { 10: t.complete("failure", error); 11: } 12: else { 13: var data = 14: { 15: uri: response.request.uri.href, 16: length: body.length 17: }; 18: t.complete("success", data); 19: } 20: }); 21: }); 22: }; 23:  24: var main = eval(Wind.compile("async", function() { 25: for(var i = 0; i < args.length; i++) { 26: try 27: { 28: var result = $await(requestBodyLengthAsync(args[i])); 29: console.log( 30: "%s: %d.", 31: result.uri, 32: result.length); 33: } 34: catch (ex) { 35: console.log(ex); 36: } 37: } 38: 39: console.log("Finished"); 40: })); 41:  42: main().start();   Run our new application. At the beginning we will see the compiled and generated code by Wind. Then we can see the pages were requested one by one, and at the end the finish message was printed. Below is the code Wind generated for us. As you can see the original code, the output code were shown. 1: // Original: 2: function () { 3: for(var i = 0; i < args.length; i++) { 4: try 5: { 6: var result = $await(requestBodyLengthAsync(args[i])); 7: console.log( 8: "%s: %d.", 9: result.uri, 10: result.length); 11: } 12: catch (ex) { 13: console.log(ex); 14: } 15: } 16: 17: console.log("Finished"); 18: } 19:  20: // Compiled: 21: /* async << function () { */ (function () { 22: var _builder_$0 = Wind.builders["async"]; 23: return _builder_$0.Start(this, 24: _builder_$0.Combine( 25: _builder_$0.Delay(function () { 26: /* var i = 0; */ var i = 0; 27: /* for ( */ return _builder_$0.For(function () { 28: /* ; i < args.length */ return i < args.length; 29: }, function () { 30: /* ; i ++) { */ i ++; 31: }, 32: /* try { */ _builder_$0.Try( 33: _builder_$0.Delay(function () { 34: /* var result = $await(requestBodyLengthAsync(args[i])); */ return _builder_$0.Bind(requestBodyLengthAsync(args[i]), function (result) { 35: /* console.log("%s: %d.", result.uri, result.length); */ console.log("%s: %d.", result.uri, result.length); 36: return _builder_$0.Normal(); 37: }); 38: }), 39: /* } catch (ex) { */ function (ex) { 40: /* console.log(ex); */ console.log(ex); 41: return _builder_$0.Normal(); 42: /* } */ }, 43: null 44: ) 45: /* } */ ); 46: }), 47: _builder_$0.Delay(function () { 48: /* console.log("Finished"); */ console.log("Finished"); 49: return _builder_$0.Normal(); 50: }) 51: ) 52: ); 53: /* } */ })   How Wind Works Someone may raise a big concern when you find I utilized “eval” in my code. Someone may assume that Wind utilizes “eval” to execute some code dynamically while “eval” is very low performance. But I would say, Wind does NOT use “eval” to run the code. It only use “eval” as a flag to know which code should be compiled at runtime. When the code was firstly been executed, Wind will check and find “eval(Wind.compile(“async”, function”. So that it knows this function should be compiled. Then it utilized parse-js to analyze the inner JavaScript and generated the anonymous code in memory. Then it rewrite the original code so that when the application was running it will use the anonymous one instead of the original one. Since the code generation was done at the beginning of the application was started, in the future no matter how long our application runs and how many times the async function was invoked, it will use the generated code, no need to generate again. So there’s no significant performance hurt when using Wind.   Wind in My Previous Demo Let’s adopt Wind into one of my previous demonstration and to see how it helps us to make our code simple, straightforward and easy to read and understand. In this post when I implemented the functionality that copied the records from my WASD to table storage, the logic would be like this. 1, Open database connection. 2, Execute a query to select all records from the table. 3, Recreate the table in Windows Azure table storage. 4, Create entities from each of the records retrieved previously, and then insert them into table storage. 5, Finally, show message as the HTTP response. But as the image below, since there are so many callbacks and async operations, it’s very hard to understand my logic from the code. Now let’s use Wind to rewrite our code. First of all, of course, we need the Wind package. Then we need to include the package files into project and mark them as “Copy always”. Add the Wind package into the source code. Pay attention to the variant name, you must use “Wind” instead of “wind”. 1: var express = require("express"); 2: var async = require("async"); 3: var sql = require("node-sqlserver"); 4: var azure = require("azure"); 5: var Wind = require("wind"); Now we need to create some async functions by using Wind. All async functions should be wrapped so that it can be controlled by Wind which are open database, retrieve records, recreate table (delete and create) and insert entity in table. Below are these new functions. All of them are created by using Wind.Async.Task.create. 1: sql.openAsync = function (connectionString) { 2: return Wind.Async.Task.create(function (t) { 3: sql.open(connectionString, function (error, conn) { 4: if (error) { 5: t.complete("failure", error); 6: } 7: else { 8: t.complete("success", conn); 9: } 10: }); 11: }); 12: }; 13:  14: sql.queryAsync = function (conn, query) { 15: return Wind.Async.Task.create(function (t) { 16: conn.queryRaw(query, function (error, results) { 17: if (error) { 18: t.complete("failure", error); 19: } 20: else { 21: t.complete("success", results); 22: } 23: }); 24: }); 25: }; 26:  27: azure.recreateTableAsync = function (tableName) { 28: return Wind.Async.Task.create(function (t) { 29: client.deleteTable(tableName, function (error, successful, response) { 30: console.log("delete table finished"); 31: client.createTableIfNotExists(tableName, function (error, successful, response) { 32: console.log("create table finished"); 33: if (error) { 34: t.complete("failure", error); 35: } 36: else { 37: t.complete("success", null); 38: } 39: }); 40: }); 41: }); 42: }; 43:  44: azure.insertEntityAsync = function (tableName, entity) { 45: return Wind.Async.Task.create(function (t) { 46: client.insertEntity(tableName, entity, function (error, entity, response) { 47: if (error) { 48: t.complete("failure", error); 49: } 50: else { 51: t.complete("success", null); 52: } 53: }); 54: }); 55: }; Then in order to use these functions we will create a new function which contains all steps for data copying. 1: var copyRecords = eval(Wind.compile("async", function (req, res) { 2: try { 3: } 4: catch (ex) { 5: console.log(ex); 6: res.send(500, "Internal error."); 7: } 8: })); Let’s execute steps one by one with the “$await” keyword introduced by Wind so that it will be invoked in sequence. First is to open the database connection. 1: var copyRecords = eval(Wind.compile("async", function (req, res) { 2: try { 3: // connect to the windows azure sql database 4: var conn = $await(sql.openAsync(connectionString)); 5: console.log("connection opened"); 6: } 7: catch (ex) { 8: console.log(ex); 9: res.send(500, "Internal error."); 10: } 11: })); Then retrieve all records from the database connection. 1: var copyRecords = eval(Wind.compile("async", function (req, res) { 2: try { 3: // connect to the windows azure sql database 4: var conn = $await(sql.openAsync(connectionString)); 5: console.log("connection opened"); 6: // retrieve all records from database 7: var results = $await(sql.queryAsync(conn, "SELECT * FROM [Resource]")); 8: console.log("records selected. count = %d", results.rows.length); 9: } 10: catch (ex) { 11: console.log(ex); 12: res.send(500, "Internal error."); 13: } 14: })); After recreated the table, we need to create the entities and insert them into table storage. 1: var copyRecords = eval(Wind.compile("async", function (req, res) { 2: try { 3: // connect to the windows azure sql database 4: var conn = $await(sql.openAsync(connectionString)); 5: console.log("connection opened"); 6: // retrieve all records from database 7: var results = $await(sql.queryAsync(conn, "SELECT * FROM [Resource]")); 8: console.log("records selected. count = %d", results.rows.length); 9: if (results.rows.length > 0) { 10: // recreate the table 11: $await(azure.recreateTableAsync(tableName)); 12: console.log("table created"); 13: // insert records in table storage one by one 14: for (var i = 0; i < results.rows.length; i++) { 15: var entity = { 16: "PartitionKey": results.rows[i][1], 17: "RowKey": results.rows[i][0], 18: "Value": results.rows[i][2] 19: }; 20: $await(azure.insertEntityAsync(tableName, entity)); 21: console.log("entity inserted"); 22: } 23: } 24: } 25: catch (ex) { 26: console.log(ex); 27: res.send(500, "Internal error."); 28: } 29: })); Finally, send response back to the browser. 1: var copyRecords = eval(Wind.compile("async", function (req, res) { 2: try { 3: // connect to the windows azure sql database 4: var conn = $await(sql.openAsync(connectionString)); 5: console.log("connection opened"); 6: // retrieve all records from database 7: var results = $await(sql.queryAsync(conn, "SELECT * FROM [Resource]")); 8: console.log("records selected. count = %d", results.rows.length); 9: if (results.rows.length > 0) { 10: // recreate the table 11: $await(azure.recreateTableAsync(tableName)); 12: console.log("table created"); 13: // insert records in table storage one by one 14: for (var i = 0; i < results.rows.length; i++) { 15: var entity = { 16: "PartitionKey": results.rows[i][1], 17: "RowKey": results.rows[i][0], 18: "Value": results.rows[i][2] 19: }; 20: $await(azure.insertEntityAsync(tableName, entity)); 21: console.log("entity inserted"); 22: } 23: // send response 24: console.log("all done"); 25: res.send(200, "All done!"); 26: } 27: } 28: catch (ex) { 29: console.log(ex); 30: res.send(500, "Internal error."); 31: } 32: })); If we compared with the previous code we will find now it became more readable and much easy to understand. It’s very easy to know what this function does even though without any comments. When user go to URL “/was/copyRecords” we will execute the function above. The code would be like this. 1: app.get("/was/copyRecords", function (req, res) { 2: copyRecords(req, res).start(); 3: }); And below is the logs printed in local compute emulator console. As we can see the functions executed one by one and then finally the response back to me browser.   Scaffold Functions in Wind Wind provides not only the async flow control and compile functions, but many scaffold methods as well. We can build our async code more easily by using them. I’m going to introduce some basic scaffold functions here. In the code above I created some functions which wrapped from the original async function such as open database, create table, etc.. All of them are very similar, created a task by using Wind.Async.Task.create, return error or result object through Task.complete function. In fact, Wind provides some functions for us to create task object from the original async functions. If the original async function only has a callback parameter, we can use Wind.Async.Binding.fromCallback method to get the task object directly. For example the code below returned the task object which wrapped the file exist check function. 1: var Wind = require("wind"); 2: var fs = require("fs"); 3:  4: fs.existsAsync = Wind.Async.Binding.fromCallback(fs.exists); In Node.js a very popular async function pattern is that, the first parameter in the callback function represent the error object, and the other parameters is the return values. In this case we can use another build-in function in Wind named Wind.Async.Binding.fromStandard. For example, the open database function can be created from the code below. 1: sql.openAsync = Wind.Async.Binding.fromStandard(sql.open); 2:  3: /* 4: sql.openAsync = function (connectionString) { 5: return Wind.Async.Task.create(function (t) { 6: sql.open(connectionString, function (error, conn) { 7: if (error) { 8: t.complete("failure", error); 9: } 10: else { 11: t.complete("success", conn); 12: } 13: }); 14: }); 15: }; 16: */ When I was testing the scaffold functions under Wind.Async.Binding I found for some functions, such as the Azure SDK insert entity function, cannot be processed correctly. So I personally suggest writing the wrapped method manually.   Another scaffold method in Wind is the parallel tasks coordination. In this example, the steps of open database, retrieve records and recreated table should be invoked one by one, but it can be executed in parallel when copying data from database to table storage. In Wind there’s a scaffold function named Task.whenAll which can be used here. Task.whenAll accepts a list of tasks and creates a new task. It will be returned only when all tasks had been completed, or any errors occurred. For example in the code below I used the Task.whenAll to make all copy operation executed at the same time. 1: var copyRecordsInParallel = eval(Wind.compile("async", function (req, res) { 2: try { 3: // connect to the windows azure sql database 4: var conn = $await(sql.openAsync(connectionString)); 5: console.log("connection opened"); 6: // retrieve all records from database 7: var results = $await(sql.queryAsync(conn, "SELECT * FROM [Resource]")); 8: console.log("records selected. count = %d", results.rows.length); 9: if (results.rows.length > 0) { 10: // recreate the table 11: $await(azure.recreateTableAsync(tableName)); 12: console.log("table created"); 13: // insert records in table storage in parallal 14: var tasks = new Array(results.rows.length); 15: for (var i = 0; i < results.rows.length; i++) { 16: var entity = { 17: "PartitionKey": results.rows[i][1], 18: "RowKey": results.rows[i][0], 19: "Value": results.rows[i][2] 20: }; 21: tasks[i] = azure.insertEntityAsync(tableName, entity); 22: } 23: $await(Wind.Async.Task.whenAll(tasks)); 24: // send response 25: console.log("all done"); 26: res.send(200, "All done!"); 27: } 28: } 29: catch (ex) { 30: console.log(ex); 31: res.send(500, "Internal error."); 32: } 33: })); 34:  35: app.get("/was/copyRecordsInParallel", function (req, res) { 36: copyRecordsInParallel(req, res).start(); 37: });   Besides the task creation and coordination, Wind supports the cancellation solution so that we can send the cancellation signal to the tasks. It also includes exception solution which means any exceptions will be reported to the caller function.   Summary In this post I introduced a Node.js module named Wind, which created by my friend Jeff Zhao. As you can see, different from other async library and framework, adopted the idea from F# and C#, Wind utilizes runtime code generation technology to make it more easily to write async, callback-based functions in a sync-style way. By using Wind there will be almost no callback, and the code will be very easy to understand. Currently Wind is still under developed and improved. There might be some problems but the author, Jeff, should be very happy and enthusiastic to learn your problems, feedback, suggestion and comments. You can contact Jeff by - Email: [email protected] - Group: https://groups.google.com/d/forum/windjs - GitHub: https://github.com/JeffreyZhao/wind/issues   Source code can be download here.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • How do I stop linux from trying to mount android phone as usb storage?

    - by user1160711
    When I plug in my Motorola Triumph to my fedora 17 linux box USB port, I get an endless series of errors on the linux box as it desperately attempts to mount the phone as a USB drive. Stuff like this: Jun 23 10:26:00 zooty kernel: [528926.714884] end_request: critical target error, dev sdg, sector 4 Jun 23 10:26:00 zooty kernel: [528926.715865] sd 16:0:0:1: [sdg] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jun 23 10:26:00 zooty kernel: [528926.715869] sd 16:0:0:1: [sdg] Sense Key : Illegal Request [current] Jun 23 10:26:00 zooty kernel: [528926.715872] sd 16:0:0:1: [sdg] Add. Sense: Invalid field in cdb Jun 23 10:26:00 zooty kernel: [528926.715876] sd 16:0:0:1: [sdg] CDB: Read(10): 28 20 00 00 00 00 00 00 04 00 If I go ahead and tell the phone to allow linux to mount the USB storage, the messages stop, and I get a mounted drive, but if all I want to do is use the debug bridge, my log on linux will continue to fill with this junk. Is there some udev magic I can do to make the system ignore this particular device as far as usb storage goes? I just noticed that if I tell the phone to enable USB storage, let linux recognize the new disk, then tell the phone to disable USB storage again, I get one additional log message about capacity changing to zero, but the endless spew of messages stops, so I guess one work around is to enable and disable USB right away.

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  • MongoDB and GrifFS. What are the best storage options in the range of 1 TB?

    - by Nerian
    We are going to launch a service that will require between 1 and 2 GB for file storage per paid user. I am going to use GridFS for storing files. I am pondering the different options for storing the database. But since I am unexperienced at deployment and it is my first time with Mongodb I need your experience. Criteria: I want to spend my time developing my core business, that is, my own application. I am a Ruby on Rails developer. I do not like to mess with server configuration. Hence, I would like a fully managed hosting solution. But I would like to know about any other option, if you think it is worth it. It should be able to scale. Cloud style. Pay as you go. The lower the price, the better. So far I known of these services: https://mongohq.com/pricing https://mongomachine.com/pricing https://mongolab.com/about/pricing/ http://cloudcontrol.com/add-ons/mongodb/ And they seem to be OK for common needs, that is no file storage. But I am going to use GridFS, so the size matters. These services seems to scale, in price, quite poorly. MongoHQ: The larger plan max storage is 20 GB. Seems like a very little storage, for GridFS. MongoMachine: Flat price, 2.5$ per GB. I didn't found the limit. Seems like a good price, comparing the others. MongoLab: 3.984 GB max, which I don't think I will hit, so perfect. 8$ per GB, quite costly. CloudControl: The larger plan is 20 Gb. The custom service starts at 250€ plus some unspecified charge per GB. What is your experience with these services? Any downtimes? Other possibilities?

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