The VMkernel logs will fill with ATS Miscompare or Status: Op: 0x89 messages. How to Troubleshoot and Fix
If the host cannot "set" the lock, it cannot write to the disk.
Ensure your HBA (Host Bus Adapter) drivers and the storage array firmware are on the vendor's "Compatibility Matrix." The VMkernel logs will fill with ATS Miscompare
The host checks the current metadata of a disk block to see if it matches what it expects.
Look for spikes in command latency. ATS is very sensitive to timing; if the storage is overloaded, ATS failures will increase. Look for spikes in command latency
To understand the error, we first have to understand the mechanism. is a hardware-offloaded locking mechanism (often part of the VAAI—vSphere Storage APIs for Array Integration—feature set in VMware environments).
In the world of distributed systems, high-availability clusters, and storage area networks (SANs), data integrity is the highest priority. One of the most cryptic yet significant errors a systems administrator or storage engineer might encounter is: is a hardware-offloaded locking mechanism (often part of
The "atomic test and set of disk block returned false for equality" error is a protective measure. While it causes disruptive downtime, it exists to prevent the "silent killer" of enterprise computing: By failing the operation when the state doesn't match, the system ensures that two hosts never write to the same block simultaneously, preserving the integrity of your databases and virtual machines.
The host may mark the storage as "All Paths Down" (APD) or "Permanent Device Loss" (PDL) to protect data integrity.