How do you respond to a failed disk in an ONTAP system?

• A. Replace the failed disk, and ONTAP will automatically resilver/rebuild the data onto the new disk.
• B. Reformat the disk and re-add it to the pool.
• C. Ignore it if redundant data exists.
• D. Power cycle the system and wait for auto-healing.

Answer: (A)

When a disk fails, you should replace it with a spare. ONTAP then uses the remaining disks in the RAID group to reconstruct the lost data onto the new disk, performing a rebuild (resilver) in the background. This keeps data available as long as there is redundancy and a spare. Reformatting or re-adding the disk isn’t how recovery is done, and simply power cycling won’t trigger the rebuild or recover the data. The automatic rebuild is how ONTAP maintains data integrity after a disk replacement.