I have a 50 TB SQL server to host on Azure. I want to benefit from the premium storage caching (mentioned in the Azure best practices for SQL VM) but then I will have to use P30 at most and a lot of them.
The other option is to use P70-80 disks but then I won't be able to benefit from the premium storage caching.
So, the question is, is the storage caching worth it? Or is it just a way to increase the IOPS?
Yes, Storage caching is worth it as without caching, the IOPS and MBps throughput counts against the virtual machine's uncached disc throughput limitations. The maximum cached limits provide readers an extra buffer, which helps with growth and unexpected peaks.
Premium caching should be used if the option is available to considerably enhance read performance against the data disc without incurring additional costs.
Virtual machines can expand beyond the remote storage uncached VM IOPS and throughput restrictions when caching is enabled on premium storage.
Note : Disk Caching is not supported for disks 4 TiB and larger (P50 and larger). If multiple disks are attached to your VM, each disk that is smaller than 4 TiB will support caching. For more information, see Disk caching.
Example:
The cache's size is determined by the virtual machine's size. The Standard M8ms VM, for example, has a total cache capacity of 793 GiB and offers 10000 cached disc IOPS and 1000 MBps cached disc throughput. Similarly, with a total cache size of 3174 GiB, the Standard M32ts VM provides 40000 cached disc IOPS and 400 MBps cached disc throughput.
