Is the filesystem on Azure Websites distributed?

Question

I know that other storage solutions are preferred for virtually any non-static data.

However, I still see some people using the filesystem provided in the Azure Websites service, which currently amounts to 10GB of space, particularly for die-hard App_Data uses.

• Is it truly distributed, or does it simply not scale at all? I'm really having trouble finding a definitive answer on this.

Out of curiosity, if it isn't:

• Is it at least replicated?
• If so, is it replicated among the instances, or is it a completely dedicated service?

If it isn't replicated either,

• Is there one master instance we should hope would never die, or is it, again, a dedicated service completely isolated from the application instances?

Thanks.

Answer 1

The file system that is used by Windows Azure Web Sites sits on top of Windows Azure BLOB Storage. They expose the space as something similar to a SMB Share that the instances running the websites point to. So, as far as replication goes, there are three copies of the data just as there are three copies of all things in BLOB storage. The storage accounts that hold this data are maintained and owned by Microsoft, it isn't in your own subscription which is one of the reasons that you are capped to the 10GB of space across all of your websites in a subscription. I'm not sure if they have geo replication turned on for their storage accounts, but my guess is that they do.

Like anything though, I'd highly recommend a process to backup anything you put into this space. You have access to it via FTP so I'd either ensure a process that maintains a backed-up copy somewhere else as files are being pushed up, or a process that can go fetch what's out there on a regular basis. This isn't a reflection of the service quality, just good practice.

UPDATE: They have a out of the box backup option now as well: http://azure.microsoft.com/en-us/documentation/articles/web-sites-backup/