Multiple VM's using the same storage accounts in Azure

Question

I read on the Azure docs that its a best practice to have 1 storage account per VM storage for performance benefenits, but on another page I read that this doesn't really become an issue untill reaching 20-40 VM in 1 storage account.

see: https://gallery.technet.microsoft.com/scriptcenter/Azure-Count-VHDs-Per-6a44ecbd

I'm planning on using 2-3 VM's with 2 SSD disks/Premium Storage each using the same storage account, my argument to keep them in the same storage account is that less resource to manage is easier management. Will I hit performance limits when using SSD's?

Answer 1

Several days ago Azure added the 'managed disks' thing which will handle all of the storage optimizations for you, I believe this is a no brainer, unless you think you can do it better ;)

Reference: https://docs.microsoft.com/en-us/azure/storage/storage-managed-disks-overview

To add to the above, those guidelines do differ, because of the Scale Sets\\Availability sets (those numbers are for Scale Sets). I believe it is recommended to have 1 VM = 1 Storage Account for standalone VM's.

Also, for premium storage: A premium storage account has a maximum total throughput rate of 50 Gbps. The total throughput across all of your VM disks should not exceed this limit.

If you are planning on doing backups - you should take this into account, as those IOPS will also hit your storage account.

Reference: https://docs.microsoft.com/en-us/azure/storage/storage-scalability-targets#scalability-targets-for-virtual-machine-disks

Answer 2

With Premium Storage, this isn't a concern: Every disk created has guaranteed IOPS and throughput. No need at all to split across multiple Premium Storage accounts, since there's no competing resources.

With standard blob storage, it really comes down to competing IOPS (not throughput), since a normal storage account maxes out at 20K transactions per second.

As mentioned in another answer, Managed Disks abstract this issue away, but it's still a good thing to understand what's happening behind the scenes.