Atomic Test And Set Of Disk Block Returned False For Equality [PREMIUM – Overview]

The "Atomic test and set of disk block returned false for equality" error in VMware vSphere indicates a failure in Hardware Assisted Locking (ATS) due to outdated storage metadata, usually caused by concurrency conflicts or high latency. This failure occurs when an ESXi host attempts to update a storage block that has already been modified by another host, requiring investigation into firmware compatibility or disabling ATS heartbeats. For a detailed technical breakdown of this specific issue, review the discussion at Reddit .

When the system reports that this operation "returned false for equality," it means the phase failed. The "Atomic test and set of disk block

: Under extreme latency, an ATS command might time out. The host assumes the write failed and tries again using the old "test" image. However, if the first write actually made it to the disk just before being aborted, the second attempt will fail because the disk has already changed. High Concurrency Overload When the system reports that this operation "returned