Atomic Test And Set Of Disk Block Returned False For Equality Jun 2026

TEST FAILED. SUBJECT ELIAS DETECTED. SETTING EQUALITY TO ZERO.

Multiple ESXi hosts are trying to access or update the same metadata block at the same time .

The Test-and-Set instruction is defined by the following atomic (indivisible) sequence: TEST FAILED

This occurs during an operation, a hardware-accelerated locking primitive where a host attempts to claim or update metadata on a shared storage array. When the "test" (checking if the block's current value matches what the host expects) fails—returning false for equality —it means another host likely changed that block since it was last read, causing a miscompare . Feature Overview: VAAI Atomic Test and Set (ATS)

Check if multiple hosts are logging the error for the exact same volume ID (UUID) simultaneously, which points to a contention or fabric issue. Step 2: Correlate with Infrastructure Events Multiple ESXi hosts are trying to access or

To understand the error, we must first break down the three core concepts:

The host checks if the disk block contains a specific value (the "expected" state). Feature Overview: VAAI Atomic Test and Set (ATS)

The system said, "I’ll take this block if it’s currently empty (0)."

“The atomic test-and-set operation on the disk block returned false when checking for equality, indicating that the current value in the block did match the expected value. This suggests a concurrent modification or a stale expected value — the operation failed as designed, preventing a potential race condition or lost update.”

grep -i "atomic test and set" /var/log/messages dmesg | grep -i "compare.*write\|reservation" journalctl -xe | grep "false for equality"

On Terminal 42, a single line of crimson text bled across the screen: