Hi,
This File Storage is the total amount of space you have to store your site and content. If you reach the quota limit, you simply can’t write any new content to the system, I would suggest you change your azure website hosting plan mode, or reduce usage
of file system storage below the File System Storage usage quota.
Please see the resource quotas here and pricing details.
http://azure.microsoft.com/en-us/pricing/details/websites/
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