ASP.NET Debugging : Azure

Azure: There is not enough space on the disk

Tom — Fri, 04 Dec 2009 16:55:14 GMT

Problem

There may be some times where you will see this message when developing an application for Windows Azure. The message will look like:

There is not enough space on the disk.
Description: An unhandled exception occurred during the execution 
of the current web request. Please review the stack trace for more 
information about the error and where it originated in the code. 

Exception Details: System.IO.IOException: There is not enough 
space on the disk.


Source Error: 
An unhandled exception was generated during the execution of the 
current web request. Information regarding the origin and location 
of the exception can be identified using the exception stack trace 
below. 

Stack Trace: 
  
[IOException: There is not enough space on the disk.]
   System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) +10546789
   System.IO.FileStream.WriteCore(Byte[] buffer, Int32 offset, Int32 count) +10351324
   System.Web.TempFile.AddBytes(Byte[] data, Int32 offset, Int32 length) +26
   System.Web.HttpRawUploadedContent.AddBytes(Byte[] data, Int32 offset, Int32 length) +327
   System.Web.HttpRequest.GetEntireRawContent() +515
   System.Web.HttpRequest.GetMultipartContent() +72
   System.Web.HttpRequest.FillInFormCollection() +248
   System.Web.HttpRequest.get_Form() +79
   System.Web.HttpRequest.get_HasForm() +73
   System.Web.UI.Page.GetCollectionBasedOnMethod(Boolean dontReturnNull) +54
   System.Web.UI.Page.DeterminePostBackMode() +90
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +268

The typical situation where you will see this is if you are using the ASP.NET FileUpload control to let users upload files.

If the file they try to upload exceeds 100 MB, it will error with this message.

Resolution

There are a few ways that you can work around this issue. The best solution would be to use Silverlight to handle the upload instead of the ASP.NET FileUpload control. By using Silverlight, you can have the client directly upload the file to blob storage and reduce how many places the file gets copied.

There are also some 3rd party controls that you can use to do this as well.

More Information

The problem with the ASP.NET FileUpload control is that it writes the file to a temp folder during upload. The folder that is used in Windows Azure is limited to 100 MB so if you try to write something larger then that, it will fail.

I haven’t tested this, but if you have multiple users uploading data at the same time, you could see the same problem. For example, if 15 users all upload a 10 MB file at the same time, the temp folder will probably fill up and give the same error.

Note: there is a setting that you may be temped to use which is the tempDirectory attribute off the compilation element. If you try to set this to anything, it will cause your Web Role to not start up.

Updates to Windows Azure from PDC

Tom — Mon, 30 Nov 2009 19:06:15 GMT

Wow there have been a lot of updates to the Windows Azure Platform that were announced at the PDC. I would love to hear from folks to let me know what they are most excited about. I was most impressed with the announcement of Dallas. I think that has the potential to change the way that we get information and consume it. It is great that companies like NASA can expose lots of information to people in a structured manner and allow the consumer to decide what they want to do with it.

I have been looking into the methods to debug applications in Windows Azure and hope to be able to talk about that very soon on this blog. So stay tuned for that and please let me know if you have any ideas of the types of data/information you would like to see.

Developing for the Clouds

Tom — Thu, 18 Jun 2009 18:33:28 GMT

I wanted to start a conversation with everyone on the thoughts around Cloud Computing. I have been using Azure for a while now and I have found some interesting things out about it.

Before I start talking about those things though, I wanted to see who was planning on using this technology or who is already using it. This would include other Cloud solutions as well.

If you are, what are you planning to do in the Cloud? How are you going about setting up testing, development, maintaining, monitoring in the Cloud?

I think that Cloud Computing is the future in a lot of ways and feel like things are going to change in a fundamental way in the not to distant future because of Cloud Computing. Do you agree?

Please keep in mind that I am not saying that Cloud Computing is a whole new way methodology, but I do think it will enable scenarios that weren’t possible before and will allow us to push the envelope of what we are capable of doing with a computer.

I look forward to hearing back from you and talking more about Azure and Cloud Computing.

Logging modules for ASP.NET (MVC) and also for Windows Azure

Tom — Fri, 24 Apr 2009 17:07:20 GMT

I was just reading through Scott Hanselman’s post about ELMAH and this sounds like a great idea. Getting a easy to consume report of all of your exceptions is a wonderful thing, especially when you add in that you can get it as an RSS feed, an email or a web site. You can check out ELMAH or read through his post to get a lot of details on it.

The web site looks like this:

This also got me thinking about Windows Azure and some of the logging that has been done already for that. So I wanted to highlight one of the projects here and talk about what it does. It is called Azure Application Monitor.

This allows you to see how much time and memory your instance is using. After you integrate this into your application, you will get a report like:

It is easy to add this to your application.

Download the application
Add the following line to your code. If you are adding it to a WebRole, add it in the Page_PreRender() function. Or in the Start() of a WorkerRole, changing it to WorkerRole below:
```
Neudesic.Azure.AzureMonitor.Start("AppName", "WebRole");
```
Be sure you have the TableStorageEndpoint configuration setting configured.
Create a PerfCounterUpdateInterval configuration setting and set the value (the value is in ticks (1000 ticks = 1 second)
Test and deploy your application

To view the data, you need to configure the AzureMonitor so that it points to your TableStorageEndpoint

As for what all it tracks, here is the list:

Application Name (you supply this in your code)

Role Name (you supply this in your code)

Machine Name

Process ID

Thread count

Handle count

Total processor time

User processor time

Private memory size

Non-paged memory size

Paged memory size

Paged system memory size

Peak paged memory size

Peak virtual memory size

Peak working set

Page file usage

Peak page file usage

Non-paged Pool Usage

Local machine time

Process local start time

It is rather easy to add more stuff to this as the code is available from the projects location.

One a side-note, if you want to see what data you have in your Blobs, Queues and Tables, there is an updated version of Azure Storage Explorer available now. From that site:

The most current release of Azure Storage Explorer, version 2.0, has several improvements over the original version:

The UI is WPF-based and has Outlook-style navigation.
Multiple storage accounts are supported, and you can change your storage account details directly in the tool.
In addition to text and byte views of items, blob items that are pictures can be viewed as images.

Azure Storage Explorer 2.0 does not presently allow you to act on storage items. This capability is being considered for a future update.

Let me know what you think or if you use any other tools for ASP.NET or Windows Azure.

Windows Azure

Tom — Wed, 11 Mar 2009 06:04:28 GMT

I have been looking into Windows Azure a lot more lately and wanted to post a little bit about some of the things that I have found out so far. It is certainly a new way of thinking of things and will take some careful thought.

Azure Tables

The first big difference is if you decide to use Azure Tables to store your data. Here is the official verbiage on them:

Windows Azure Table – Programming Table Storage
Windows Azure Table provides scalable, available, and durable structured storage in the form of tables. The tables contain entities, and the entities contain properties. The tables are scalable to billions of entities and terabytes of data, and may be partitioned across thousands of servers. The tables support ACID transactions over single entities and rich queries over the entire table. Simple and familiar .NET and REST programming interfaces are provided via ADO.NET Data Services.

So what does this all mean to you? Well, when you create a table, there are two important “columns” that you need to concern yourself with. The PartitionKey and the RowKey

PartitionKey

The PartitionKey a string that we use to split up the data. For example, if we were creating a table that would store news articles, the PartitionKey may be the section header (Top News, Sports, Weather, etc). We can then take each of these groupings and put each individual one on a different server. This is part of how we can scale.

RowKey

The RowKey is also a string that we use to sort the data. This needs to be a unique entry for each row of data. The most common thing to use so far has been some form of date entry. This is what we use by default to sort the data. So if you use the ticks of the current timestamp, then all your data will show up with the oldest entry first. If you want them to show up the other way around, one easy way to make that happen is to subtrace the current timestamp from the DateTime.MaxValue and then get the ticks from that. Just please remember to use UTC times!

Azure Queues

When you get data from a user and want to enter it into the data backend, there are a few ways to handle it. The major reason that I see for using a queue is for the situation where something happens while entering data into the back end. If you just enter the data directly from the web site’s code, you can get into a situation where some tables are updated and others are not. If you instead place the data into a queue and then have a Worker Role process that pulls that out of the queue, if there is a problem then the message will still be in the queue and the next Worker Role process can pull it out and process it.

This isn’t without it’s own set of problems however.

If you have updated some data, when you try to insert into a table you can get an error that the data already exists. So you need to check for that and call update instead.
You then have a problem where the data may have existed when you attempted to insert it again, but it was then deleted before you tried to update so that also fails. So to handle that, you need to put the insert/update attempt into a loop to ensure it happens.
What if the reason that a Worker Role crashes or doesn’t complete is because the message is causing the problem (corrupt data)? Then you need to have a way to check when you are processing a message to see if the timestamp when the message was entered into the database was a certain time in the past. If that is the case, then you know that the message is bad so just delete it.

Azure Blobs

Blobs are a really interesting concept where you can store named files in the cloud. You can also store metadata for these files. One way that this can be used is to store the images used on your website. Typically they have always been stored in a subdirectory of your website. The problem with doing that is that the package that you use to deploy your website to Azure will then have these images. This means if you want to update your images, you have to redeploy the entire package. If you instead store them in blob storage, you can then update them whenever you want and it doesn’t affect the website at all.

You can use the name of the file to include a \ in it and treat those like folders. So if you had music files you were storing, you could put it in as a file name called “rock\myrocksong.mp3”. You could then do queries to pull out all the “rock” files.

How Do I Videos

There are some great “How Do I” videos available for Windows Azure, be sure to check them out.

Going forward

I am going to continue to look into Windows Azure and some of the other pieces of Azure and will post things as I figure them out. I already have a few tips that I have been looking at, but I want to get a few more before I start posting them. Let me know what you think of Azure and any of these things.

Cloud applications

Tom — Mon, 16 Feb 2009 05:48:14 GMT

Now that we are getting closer to releasing Windows Azure, I wanted to check and see who is planning to have an application in the cloud. Or if you already have an application in the cloud, what you are doing there and how it is working for you.

Please note, I understand that other companies are hosting cloud applications and by no means am I wanting to compare the hosters. I want to focus on the types of applications you are using or planning on using.

Feel free to discuss it here and what advantages you think it has over traditional applications. To get things started, here are some companies plans. This is all from:

http://www.microsoft.com/azure/casestudies.mspx

Enterprise Content Management Company to Reach More Customers with Cloud Computing

Open Text Corporation, a global leader in enterprise content management, realized that customers increasingly demand more flexible and affordable ways of managing their electronic archiving environments. The company is integrating its software with the Azure™ Services Platform—a cloud-computing platform from Microsoft―to provide a virtual storage service. This will speed implementation, improve business.

UK-Based Incubator Develops Social Discovery and Messaging Application on the Azure Services Platform

Bluehoo has created and deployed a social discovery and messaging application that lets people use their mobile phones to find other users around them with similar interests. To ensure that they have a reliable and scalable foundation for their business, Bluehoo built their application on the Azure Services Platform.

Mashups Showcase from Live Services

Windows Live Services allow for the easy creation of mashups—applications that combine data or content from several sources into a new single integrated application. Check out mashups for Live Services in this showcase.

What do you need to troubleshoot Azure?

Tom — Wed, 19 Nov 2008 14:00:00 GMT

Looking to the future with cloud computing, it is going to become increasingly important to have good information about what is happening with your site in order to properly maintain it.

Keeping development type of issues aside, what types of things do you think you will need in order to be able to properly troubleshoot a problem in your application once it is deployed to the cloud.

For example, when you publish your application, it will be similar to uploading today to a hoster in that:

No access to the server
Cannot get dumps of any processes
Cannot access perfmon logs
Cannot access the Event log

So given that type of situation:

What are the possible problem situations that may arise?
What types of information do you think you will require to find out what is going wrong with your application?
Would you try to pull your application onto your development box to try to repro some of the problems that way?

Or are there any other concerns or thoughts you have around this? I’d love to hear what you have to say.

Insides of Azure

Tom — Fri, 14 Nov 2008 14:00:00 GMT

Want to get more details about Windows Azure? There is a really helpful video done by Channel 9 that talks about this upcoming product and how it works.

I think this gives great details about the architecture and also how you will use this and what it will be good for. Check it out:

Dharma Shukla: Inside Live Framework

There are a bunch of other details you can find out about this product so feel free to post your favorites in the comments.

Windows Azure and you

Tom — Tue, 11 Nov 2008 14:00:00 GMT

So I have started to look at the new Windows Azure that we just announced, you can download the framework from here. You can also read more about it at Azure Services Platform Developer Center.

As I started looking at this, the main sample I was focused on was the PersonalWebSite Sample. It gives me a pretty good idea of how it is going to be to develop for this platform. But I haven’t been able to fully look into what it is going to be like to troubleshoot it. Especially from a production viewpoint.

Have you looked at this new platform yet? What are your thoughts?