Automatic space reclamation doesn't work on VMFS6 with unmap granularity greater than 1 MB
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Article ID: 314380
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Updated On:
Products
VMware vCenter ServerVMware vSphere ESXi
Issue/Introduction
Symptoms:
You are using thin-provisioned storage arrays with ESXi and VAAI Delete Status is supported on the Storage Array.
You have set the Space reclamation priority as low.
The host cannot automatically issue the T10 unmap command from VMFS6 and VM guest operating systems to reclaim unused space from the array.
ESXi supports automatic storage space reclamation on VMFS6 datastores but its not working for the storage arrays with unmap granularity greater than 1 MB.
Environment
VMware vSphere ESXi 6.# VMware vSphere ESXi 7.# VMware vSphere ESXi 8.# VMware vCenter Server 6.# VMware vCenter Server 7.# VMware vCenter Server 8.#
Resolution
ESXi does not support the automatic space reclamation on arrays with unmap granularity greater than 1 MB. If the unmap granularity of the backing storage is greater than 1 MB, the unmap requests from the ESXi host are not processed.
You need to verify the File Block Size on the Storage Array which should not be greater than 1 Mb.
For more information on Auto Unmap feature and its limitations, see UNMAP section in vSPhere 7.0 Storage.