VSAN-Troubleshooting-Reference-Manual

Diagnostics and Troubleshooting Reference Manual – Virtual SAN
VM behavior when multiple failures are encountered
An object remains accessible when a full mirror copy is available, and greater than
50% of the components or votes are available. The witnesses are there to assist with
the latter requirement.
The behavior when there are more failures in the cluster than the
NumberOfFailuresToTolerate setting is discussed here next.
VM powered on and VM Home Namespace object goes inaccessible
If a running VM has its VM Home Namespace object go inaccessible due to failures in
the cluster, a number of different things may happen. One of these includes the VM
process crashing resulting in the VM powering off. Once the VM is powered off, it
will be marked "inaccessible" in the vSphere web client UI. There can also be other
side effects, such as the VM getting renamed in the UI to its vmx path rather than VM
name, or the VM being marked "orphaned".
VM powered on and disk object goes inaccessible
If a running VM has one of its disk objects go inaccessible, the VM will keep running,
but its VMDK has all its I/O stalled. Typically, the Guest OS will eventually time out
I/O. Some Windows versions may BSOD when this occurs. Many Linux distributions
typically downgrade the filesystem on the VMDK to read-only.
The Guest OS behavior, and even the VM behavior is not Virtual SAN specific. This is
simply ESXi behavior to APD (All Paths Down).
Once the VM becomes accessible again, the status should resolve, and things go back
to normal. Of course, nothing ever gets corrupted.
Commands to examine the state of the network and storage will be seen shortly, and
these will help to make a decision about what corrective action is needed to resolve
VM accessibility issues.
V M W A R E S T O R A G E B U D O C U M E N T A T I O N / 61