Disk Block Returned False For Equality — Atomic Test And Set Of

It looked at the block and found something else (1), likely because another process got there a millisecond faster.

Think of it as a "surgical lock." In older systems, if a host wanted to update a piece of metadata on a shared datastore, it had to lock the entire LUN (SCSI Reservation), preventing every other host from talking to that storage. ATS changed this by allowing a host to lock only a specific disk block It looked at the block and found something

If you want, I can produce a short implementation sketch (pseudo-code) for retry + read-after-write verification, or a logging schema for the detailed logs. Which would you prefer? Which would you prefer

It occurs when a host attempts to update a disk block (such as a VMFS metadata heart-beat) but finds that the data currently on the disk does not match what it expected to see before making the change . Core Mechanism: Atomic Test and Set (ATS) If the values match, the operation proceeds (equality

: ATS works by comparing the current state of a disk block to an "expected" value. If the values match, the operation proceeds (equality is true). This error means the comparison failed because the disk block's actual data did not match what the host expected, suggesting another host modified it first or there is a communication desync.