Let’s discuss about to reclaim the thin provisioned datastore.
Common types of VMDK Disk types:
Eager Zeroed Thick
An eager zeroed thick disk has all space allocated and wiped clean of any previous contents on the physical media at creation time. Such disks may take longer time during creation compared to other disk formats. The entire disk space is reserved and unavailable for use by other virtual machines.
Thick or Lazy Zeroed Thick
A thick disk has all space allocated at creation time. This space may contain stale data on the physical media. Before writing to a new block a zero has to be written, increasing the IOPS on new blocks compare to Eager disks. The entire disk space is reserved and unavailable for use by other virtual machines.
ThinSpace required for thin-provisioned virtual disk is allocated and zeroed on demand as the space is used. Unused space is available for use by other virtual machines.
Scenario,where you have thin provisioned the vmdk which grows whenever the usage in guest is level.All of sudden the growth of the vmdk decrease and datastore space claimed during the thin provisioned in unclaimable,there is no reverse reclaim of space by default.
1.Easy way to reclaim the thin provisioned unused space by svmotion(storage vmotion) the VM to different datastore which helps to reclaim the same without downtime.
2.VMware has provide the utility tool where the reclaim the vmfs deleted blocks using vmkstools.So how this works.
VMware 5.0 introduce VAAI storage plugin to provision the lun with thin from storage level.
More about VAAI.
Reclaim the space using vmkfstools by default is disable to avoid unnecessary stress to the storage array.
KB represents how to reclaim the space using vmkfstools -y command in 5.1 and esxcli storage vmfs unmap in 5.5