Atomic Test And Set Of Disk Block | Returned False For Equality Repack

This isn't just a log entry you can ignore. When an ATS miscompare happens, the ESXi host often loses trust in its connection to the storage. This can trigger: SCSI Resets

This occurs during an operation, a hardware-accelerated locking primitive where a host attempts to claim or update metadata on a shared storage array. When the "test" (checking if the block's current value matches what the host expects) fails—returning false for equality —it means another host likely changed that block since it was last read, causing a miscompare . Feature Overview: VAAI Atomic Test and Set (ATS)

Review your system logs (e.g., vmkernel.log in ESXi or dmesg / syslog in Linux) to map the device ID (NAA ID) associated with the failed command. Cross-reference the timestamp to find which hosts were interacting with the volume simultaneously. Step 2: Verify Storage Hardware Acceleration (ATS) Status This isn't just a log entry you can ignore

The storage array might not be responding correctly to the ATS command (VAAI primitive). Common Symptoms Datastores failing to mount or appearing as "inaccessible". Virtual machines failing to power on or off.

Get-AdvancedSetting -Entity VMHost-Name -Name VMFS3.UseATSForHBOnVMFS5 | Set-AdvancedSetting -Value 0 -Confirm:$false When the "test" (checking if the block's current

Hypervisor Storage Stack (VMFS/DLX), Storage Fabrics (FC/iSCSI), Storage Array Controller.

Ensure that multipathing policies (PSA) are correctly configured for your storage array to prevent SCSI reservation contention. Step 2: Verify Storage Hardware Acceleration (ATS) Status

Some storage devices (especially network-attached ones) do not support true atomic test-and-set across power failures or multiple initiators. If your device cannot guarantee sector-level write atomicity, you may see spurious equality failures. Switch to a device that supports NVMe’s Compare and Write or SCSI’s COMPARE AND WRITE command.

Dropped packets or high latency in the SAN can cause the host and storage to become out of sync regarding the lock state . Troubleshooting Steps

Understanding the "Atomic Test and Set of Disk Block Returned False for Equality" Error