An Azure virtual machine supports attaching a number of data disks. For optimal performance, you will want to limit the number of highly utilized disks attached to the virtual machine to avoid possible throttling. If all disks are not being highly utilized at the same time, the storage account can support a larger number disks.
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For Azure Managed Disks: Managed Disks count limit is regional for the subscription. The default soft limit is 2,000 per region per subscription. To increase your limit, contact Azure support.
Managed Snapshots and Images are counted against the Managed Disks limit.
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For standard storage accounts: A standard storage account has a maximum total request rate of 20,000 IOPS. The total IOPS across all of your virtual machine disks in a standard storage account should not exceed this limit.
You can roughly calculate the number of highly utilized disks supported by a single standard storage account based on the request rate limit. For example, for a Basic Tier VM, the maximum number of highly utilized disks is about 66 (20,000/300 IOPS per disk), and for a Standard Tier VM, it is about 40 (20,000/500 IOPS per disk), as shown in the table below.
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For premium storage accounts: 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.