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What is needed for VAAI hardware acceleration to occur?

Last Updated:

Applies to

  • SAN (Storage Area Network)
  • NFS (Network File System)
  • VAAI (vStorage API for Array Integration)


There are certain scenarios where hardware acceleration will fail and the ESXi host reverts to using native methods (software datamover) instead.  Those scenarios include:

  • For NFS, only a cold migration (VM is powered off) will be offloaded to a storage array. If a VM is powered on, ESXi will revert to a software datamover instead
  • For NFS, the 'vstorage' option on the SVM is disabled
  • For NFS, the export policy has rules that block NFSv4 RPC calls.  VAAI calls are proprietary NFSv4 RPC calls and require export policy rules to allow for both NFSv3 and NFSv4 RPC calls
  • For NFS, the NetApp NFS Plug-in for VMware VAAI plugin is not installed
  • For SAN, space reclamation (or SCSI UNMAP) requires that a LUN is thin provisioned and has space allocation enabled. If these prerequisites are not met, space reclamation cannot take place

Additionally VMware calls out additional scenarios where hardware acceleration cannot be used and the ESXi host reverts to a software datamover:


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