Unmanaged disks are the disks that most of us will be using with Azure IaaS VMs, e.g non SSD backed on an Azure Storage Account.
If you are using these “unmanaged” standard disks (HDD), you should enable TRIM. TRIM discards unused blocks on the disk so you are only billed for storage that you are actually using. This can save on costs if you create large files and then delete them.
You can run this command to check the TRIM setting. Open a command prompt on your Windows VM and type:
fsutil behavior query DisableDeleteNotify
If the command returns 0, TRIM is enabled correctly. If it returns 1, run the following command to enable TRIM:
fsutil behavior set DisableDeleteNotify 0