When a system displays the error message it indicates that a low-level synchronization command failed because the storage state changed unexpectedly. This mechanism is critical for maintaining a single source of truth across shared infrastructure. The Underlying Technology: VAAI and ATS
: It provides Hardware-Assisted Locking , allowing a host to lock only specific disk sectors/metadata blocks rather than the entire LUN. Mechanism :
To interpret this error, you must first understand three foundational concepts of modern storage virtualization.
When an ATS operation returns "false for equality," it means a mismatch occurred. This mismatch is rarely caused by a failing hard drive; it is almost always an orchestration or communication fault. 1. Multi-Host Contention and Race Conditions
Let’s dissect what this means, why it happens, and why your database cluster might refuse to talk to itself because of it. When a system displays the error message it
Resolving this error requires a systematic approach across the host, network, and storage layers. Step 1: Correlate the Timestamps
Resolving an ATS equality failure requires a systematic approach to isolate whether the issue lies in the host layer, the fabric layer, or the storage array layer. Step 1: Analyze the System Logs
A return value of false indicates that the atomic condition was not met.
To temporarily mitigate a critical array failure, you can disable ATS locking globally on a host (forcing standard SCSI locks), though this should be treated as a temporary diagnostics step: Mechanism : To interpret this error, you must
Mass storage migrations (e.g., Storage vMotion) executing simultaneously. 3. Storage Array Firmware Bugs or Outdated Drivers
: High I/O latency or intermittent connectivity issues can cause these "heartbeat" failures, leading to the host losing access to the volume. Common Symptoms
The error message is a critical alert generated within enterprise storage environments—most notably inside VMware ESXi ( vmkernel.log ) kernels. It signals a failure in Hardware Assisted Locking (VAAI ATS) , meaning that an ESXi host attempted to lock or update a specific disk block on a shared datastore, but the underlying storage array rejected the operation because the expected disk state did not match reality .
While the error manifests as a software log entry, it is almost always driven by underlying hardware bottlenecks, misconfigurations, or network instability. Storage Network Latency and Timeout Dropouts Implement Storage Queue Regulation
The error message is most prevalent within the VMware ecosystem, specifically concerning the interaction between an ESXi host and a shared storage array. This is due to VMware's implementation of the VAAI (vStorage APIs for Array Integration) Atomic Test and Set (ATS) primitive.
If the values do not match ( False for equality), the storage array rejects the write operation entirely.
Depending on your root cause analysis, apply the following technical remediations to stabilize the storage environment. Implement Storage Queue Regulation