If an ESX/ESXi host loses access to a datastore, I/O from running virtual machines on the datastore will time out and fail. The virtual machine pauses and an event message appears stating that the virtual machine lost access to its disk. This problem might occur in these situations:
- The host's storage network connection is not restored within 15 seconds and another host breaks the disk lock.
This is the expected behavior because VMFS host clustered lock manager lets a host send I/O to resources such as virtual disk files only if the host owns the resource through a lock. This process is required so that guest data remains consistent with other hosts who might try to access the same data. For more information see, Host Connectivity Degraded in ESX/ESXi (1009557).
- The host is part of a VMware HA cluster and loses connectivity to its management and storage networks (Isolation Event).
In this case, VMware HA attempts to restart virtual machines on a 'healthier' host in the cluster. If HA is configured to leave virtual machines powered on when isolated, the virtual machines on the isolated host are failed over, but the original virtual machines remain running on the isolated host (without the VMDKlocks). When the isolated host rejoins the cluster, the duplicate virtual machines running on it fail to reacquire the disk locks and the event message appears.
A node that is isolated from the network needs time to release the virtual machine's VMFS locks if the host's isolation response is to fail over the virtual machines or to leave them powered on.
In HA enabled clusters, the virtual machine will be powered-on on another host. In non-HA clusters, you can power on the virtual machine after it is powered off.
The most common reasons for the failure in updating the disk locks are intermittent SAN and network issues, such as unreachable storage or high latencies. Ensure to resolve any issues with the storage or network in your environment.
For related information, see:
For documentation regarding VMware High Availability and other related features, see:
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