Our storage vendor issued an advisory relating to Host Disconnects Using VMware vSphere 5.5.0 Update 2 and vSphere 6.0. The advisory contends that vSphere 5.5 U2 and higher has changed to using ATS locking for heartbeat I/O which causes host and VM disconnects if delays of 8 seconds or longer are experienced. 8 seconds seems like a pretty long wait for IO but I am more confused by the recommendation. They advise forcing the configuration to revert to prior heartbeat methods with the following command:
esxcli system settings advanced set -i 0 -o /VMFS3/useATSForHBOnVMFS5
My question:
My understanding is that if VMware detects VAAI support at the creation of a datastore then only ATS locking is available, with no fallback to SCSI reservations. Am I mistaken about this and should the above configuration be implemented?
Many thanks.
