In clustered environments (like VMware VMFS datastores), hosts use ATS as a "heartbeat" to tell other hosts they are still alive. If the network between the host and the storage has high latency or dropped packets, the update might arrive late or out of sync, causing the "equality" check to fail because the host is working with stale metadata. Impact on Operations When this error occurs, you will typically notice:
This happens in a single, uninterruptible operation. Decoding the Error: "Returned False for Equality"
Use command-line tools (like esxcli storage core device vaai status get ) to ensure the array is actually reporting ATS as "supported." Conclusion
The most common cause is that two different hosts are trying to access the same metadata at the exact same time. If Host A updates a block while Host B is still holding onto "old" information about that block, Host B’s next ATS command will fail because the block's state changed behind its back. 2. Storage Array Firmware Incompatibilities
Atomic Test And Set — Of Disk Block Returned False For Equality
In clustered environments (like VMware VMFS datastores), hosts use ATS as a "heartbeat" to tell other hosts they are still alive. If the network between the host and the storage has high latency or dropped packets, the update might arrive late or out of sync, causing the "equality" check to fail because the host is working with stale metadata. Impact on Operations When this error occurs, you will typically notice:
This happens in a single, uninterruptible operation. Decoding the Error: "Returned False for Equality" Decoding the Error: "Returned False for Equality" Use
Use command-line tools (like esxcli storage core device vaai status get ) to ensure the array is actually reporting ATS as "supported." Conclusion Storage Array Firmware Incompatibilities
The most common cause is that two different hosts are trying to access the same metadata at the exact same time. If Host A updates a block while Host B is still holding onto "old" information about that block, Host B’s next ATS command will fail because the block's state changed behind its back. 2. Storage Array Firmware Incompatibilities Decoding the Error: "Returned False for Equality" Use