If heartbeats fail to complete for a total of 16 seconds , the host marks the datastore as offline and logs a "Lost access to volume" event. Common Causes
While the error signals a failure, the Datastore Heartbeating feature itself is the monitoring tool. It allows vCenter to distinguish between a host that has failed entirely and one that is simply partitioned from the management network but still has active storage access. VOMA (vSphere On-disk Metadata Analyzer): esx.problem.vmfs.heartbeat.timedout
The most critical context for this error is . If heartbeats fail to complete for a total
The esx.problem.vmfs.heartbeat.timedout event indicates that an ESXi host has lost communication with a VMFS (Virtual Machine File System) datastore for a period exceeding the configured timeout threshold. This is a critical storage connectivity issue that can lead to VM stun, application failures, and potential data corruption. VOMA (vSphere On-disk Metadata Analyzer): The most critical
On some storage arrays, the use of VAAI ATS for heartbeating can lead to "false miscompares" and timeouts under high load.
Engage support if:
| Category | Specific Cause | |----------|----------------| | | Fibre Channel (FC) switch issues, Zoning misconfiguration, ISL congestion | | iSCSI/NFS | Network packet loss, high latency, MTU mismatch (jumbo frames), VLAN misconfiguration | | Storage Array | Controller failover, firmware bug, overloaded backend, snapshot/ clone operations | | ESXi Host | HBA driver/firmware mismatch, queue depth exhaustion, APD (All Paths Down) condition | | Path Issues | Dead paths, misconfigured PSP (Most Recently Used vs. Round Robin), transient SCSI sense codes |