6.5.1

Table Of Contents
Manual Reclamation of Free Space on VMFS5 Datastore
VMFS5 and earlier file systems do not unmap free space automatically, but you can use the esxcli
storage vmfs unmap command to reclaim space manually. When you use the command, keep in mind
that it might send many unmap requests at a time. This action can lock some of the resources during the
operation.
Configure Space Reclamation for a VMFS6 Datastore
When you create a VMFS6 datastore, you can modify the default parameters for automatic space
reclamation. You can also change granularity and priority or disable space reclamation for your VMFS6
datastore.
Procedure
1 In the vSphere Web Client navigator, select Global Inventory Lists > Datastores.
2 Click the New Datastore icon.
3 Follow the steps required to create a VMFS6 datastore.
4 On the Partition configuration page, specify the space reclamation parameters.
The parameters define granularity and the rate at which space reclamation operations are performed.
You can also use this page to disable space reclamation for the datastore.
Option Description
Block size The block size on a VMFS datastore defines the maximum file size and the
amount of space the file occupies. VMFS6 supports the block size of 1 MB.
Space reclamation granularity Specify granularity for the unmap operation. Unmap granularity equals the block
size, which is 1 MB.
Storage sectors of the size smaller than 1 MB are not reclaimed.
Space reclamation priority Select one of the following options.
n
Low (default). Process the unmap operations at a low rate.
n
None. Select this option if you want to disable the space reclamation
operations for the datastore.
5 Finish the datastore creation process.
After you enable space reclamation, the VMFS6 datastore can start releasing the blocks of unused space
only when it has at least one open file. This condition can be fulfilled when, for example, you power on
one of the VMs on the datastore.
Change Space Reclamation Priority
Space reclamation priority defines how blocks deleted from a VMFS6 datastores are reclaimed on a LUN
backing the datastore. By default, the LUN performs the space reclamation operation at a low rate. You
can modify the default setting to disable the operation for the datastore.
vSphere Storage
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