A storage command signalling which blocks are now unused, so that space is handed back, for example on a dynamic disk or one that is thinly provisioned.
Also called UNMAP.
In the Ultra Transcenders books
Each book explains TRIM in context, with comparison tables and the common traps.
Terms in this definition
- General-purpose v1
The older storage account kind (
Storage), which lacks access tiers, Archive and premium file shares and retires on 13 October 2026. Converting to ZRS requires first upgrading to GPv2, a one-way change. - Dynamic disk
Spanned, striped and mirrored volumes were possible with this older Logical Disk Manager format. It is now deprecated; use basic disks or Storage Spaces.
Related terms
- Space reclamation
Handing blocks that are no longer in use, after files are deleted on the datastore or inside a guest, back to the storage array using SCSI UNMAP. VMFS6 does it automatically; earlier VMFS versions relied on running an esxcli command by hand.