VMs randomly lose storage and network access after disabling ATS locking on ESXi hosts

Products

• VMware vSphere ESXi

Issue/Introduction

After migration to host clusters on which ATS locking is disabled, VMs are facing disruption of connectivity for several minutes.

Some VMs lose access to storage and/or network.

VMs may hang (with CPU soft-lock) or have kernel panics.

 

 

Environment

VMware vSphere ESXi 8.x

Cause

SCSI reservation on the whole device when ATS is disabled.

Without ATS, metadata updates trigger a global lock on the entire device, temporarily blocking I/O from other hosts and causing conflicts, retries, and high latency. 

Resolution

Enable ATS Locking on all hosts accessing the datastores (avoid running in mixed mode):

esxcli system settings advanced set --int-value 1 --option /VMFS3/HardwareAcceleratedLocking

Note: This option is effective immediately and does not need any reboot or mount/unmount of volumes.

 

 

Additional Information

To disable ATS Locking refer to Disabling hardware accelerated locking (ATS) in ESXi