What happens when an HDD fails within a Nutanix cluster?

Nutanix stores data across nodes using a Replication Factor of RF2 or RF3, ensuring that copies exist on separate drives and nodes at all times. When a disk fails, the internal Curator distributed job framework detects the drop in redundancy and automatically triggers re-replication of under-protected data extents to other available drives across the cluster, restoring full protection without manual steps.

Data remains accessible during an HDD failure because the Replication Factor guarantees that live copies exist on other nodes, so no unavailability window occurs while waiting for a disk replacement.

Data is not lost on a single HDD failure because Nutanix's RF2 or RF3 replication maintains redundant copies on separate physical nodes, preventing data loss from any single-disk failure.

Nutanix does not use dedicated hot spare disks as traditional RAID arrays do; instead it re-distributes the affected data across all healthy drives in the cluster, using spare capacity distributed throughout the system.