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An administrator is troubleshooting a vSAN issue. As part of the initial investigation, the following observations were identified:
* vSAN cluster capacity is decreased.
* Some virtual machine components are marked as degraded.
* Component rebuild process started automatically.
What is the cause of this issue?
The symptoms described---reduced cluster capacity, degraded virtual machine components, and automatic component rebuild operations---are classic indicators of a vSAN disk failure or disk group degradation. vSAN continuously monitors the health of disks, disk groups, and network paths. When a physical disk or disk group becomes unavailable, vSAN will:
Mark affected components as degraded because the required number of replicas or witnesses cannot be maintained.
Trigger automatic repair/rebuild operations, provided there are enough healthy disks remaining in the cluster to satisfy the storage policy (e.g., FTT=1, RAID1/5/6).
Reduce available storage capacity because the failed device is removed from contributing to the vSAN datastore.
These behaviors align directly with documented vSAN failure-response logic, which states that component rebuilds begin automatically after a disk failure, assuming the cluster still has adequate resources.
The other options do not match the symptoms:
A . VM migration to another cluster does not reduce vSAN capacity nor trigger component rebuilds.
B . vSAN license capacity too small restricts features, not component state or capacity changes.
C . Too many VMs created may cause capacity pressure but does not mark components degraded or trigger automated rebuilds.
Only physical disk failure accurately explains all three observations simultaneously.