Q. How do I use Premium Storage with a VM?
A. Once you have a Premium Storage account the next step is to leverage the storage account with a VM. To use Premium Storage with a VM you need to use a DS-series VM. These VMs are very similar to the D-series VMs that have SSD temporary storage instead of HDD temporary storage. The exception is that some of the SSD temporary storage is used for caching purposes to ensure the predictable levels of performance associated with Premium Storage.
DS-series VMs are available in the same regions as Premium Storage. Select a DS-series VM (select View all in the pricing tier blade) as shown. Note that the different sizes support different maximum IOPS per VM which relates to the number of data disks that can be attached and also the amount of local SSD dedicated to caching. Select a size and click the Select button then continue with the VM creation. Exact details on the DS-series VMs can be found at https://msdn.microsoft.com/en-us/library/azure/dn197896.aspx and the DS series details shows the amount of cache allocated for each of the VM sizes.
If you compare the equivalent D-series size to the DS-series size you will notice the Temporary disk size for the D-series matches the Temporary disk size + the cache size of the DS-series, for example:
- Standard D2 - 100 GB SSD temporary storage
- Standard DS2 - 14 GB SSD temporary storage and 86 GB cache size
Once the DS-series VM is created you can add additional data disks on Premium Storage (or Standard Storage). Remember that each of the DS-series sizes has a maximum amount of IOPS, therefore ensure you do not add more premium disks than can be supported by the VM size. Also remember that if you add more than 8 data disks and combine them using a Storage Space then you need to manually set the column number to the number of disks by setting the NumberOfColumns parameter when using New-VirtualDisk.