Datastore with PDL

For environments running ESXi 6.0 or later, the ability to respond to Permanent Device Loss (PDL) was added into vSphere HA.

PDL occurs when a storage volume is no longer accessible to an ESXi host—furthermore, communication between the host and array has not stopped and SCSI interaction can continue (exchange of SCSI operations and response code) but that specific volume is no longer available to that host. The array will inform ESXi that the volume is no longer accessible using specific SCSI sense codes and ESXi then will stop sending I/O requests to that volume.

More information on PDL can be found in the following VMware KB.

The default behavior of PDL response is for vSphere HA to not restart VMs on other hosts when PDL is encountered. Especially in non-Uniform configurations, Everpure recommends enabling this setting by choosing Power off and restart VMs.

In Uniform configurations, enabling this setting is less important since the volume is presented via two arrays, and full PDL would require the volume to be removed from both FlashArrays. While the accidental removal of access of the volume to a host via both arrays is less likely to occur, it is still possible and therefore Everpure recommends enabling Power off and restart VMs.