Atomic Test And Set Of Disk Block Returned False For Equality !exclusive! -

The error is not a bug—it is a safety mechanism. It signals that your storage system correctly prevented a conflicting write in a concurrent environment. However, when it occurs unexpectedly, it indicates deeper issues: stale caches, lingering reservations, misaligned architectures, or hardware faults.

ATS is a storage hardware acceleration feature (part of VAAI) used by ESXi to lock individual disk blocks rather than an entire LUN. The error is not a bug—it is a safety mechanism

: High I/O latency can lead to ATS heartbeats failing, causing the service to degrade. Firmware/Driver Incompatibility when it occurs unexpectedly

You may have computed the expected value incorrectly—for example, using a stale version number. Recompute the expected value by re-reading the block immediately before TAS, not relying on cached data more than a few milliseconds old. it indicates deeper issues: stale caches