OneFS protects data stored on failing nodes or drives through a process called smartfailing.

During the smartfail process, OneFS places a device into quarantine. Data stored on quarantined devices is read only. While a device is quarantined, OneFS reprotects the data on the device by distributing the data to other devices. After all data migration is complete, OneFS logically removes the device from the cluster, the cluster logically changes its width to the new configuration, and the node or drive can be physically replaced.

OneFS smartfails devices only as a last resort. Although you can manually smartfail nodes or drives, it is recommended that you first consult Isilon Technical Support.

Occasionally a device might fail before OneFS detects a problem. If a drive fails without being smartfailed, OneFS automatically starts rebuilding the data to available free space on the cluster. However, because a node might recover from a failure, if a node fails, OneFS does not start rebuilding data unless the node is logically removed from the cluster.