Automatic space reclamation doesn't work on VMFS6 with unmap granularity greater than 1 MB
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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 Server VMware 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.
     
  • To verify the Auto UNMAP feature support footnote for your storage, see VMware Hardware Compatibility Guide (HCL).

    Example:

 

Additional Information

VMFS 5 supports manual space reclamation.

 

For more information on space reclamation features, see ESXi and Array Thin Provisioning section in VMware vSphere 6.5 Documentation Center.