How Data ONTAP monitors disk performance and health
Data ONTAP continually monitors disks to assess their performance and health. When Data ONTAP encounters certain errors or behaviors from a disk, it takes the disk offline temporarily or takes the disk out of service to run further tests.
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What happens when Data ONTAP takes disks offline
Data ONTAP temporarily stops I/O activity to a disk and takes a disk offline when Data ONTAP is updating disk firmware in background mode or when disks become non-responsive. While the disk is offline, Data ONTAP performs a quick check on it to reduce the likelihood of forced disk failures.
How Data ONTAP reduces disk failures using Rapid RAID Recovery
When Data ONTAP determines that a disk has exceeded its error thresholds, Data ONTAP can perform Rapid RAID Recovery by removing the disk from its RAID group for testing and, if necessary, failing the disk. Spotting disk errors quickly helps prevent multiple disk failures and allows problem disks to be replaced.
How the maintenance center works
When a disk is in the maintenance center, it is subjected to a number of tests. If the disk passes all of the tests, it is redesignated as a spare. Otherwise, Data ONTAP fails the disk.
When Data ONTAP can put a disk into the maintenance center
When Data ONTAP detects certain disk errors, it tries to put the disk into the maintenance center for testing. Certain requirements must be met for the disk to be put into the maintenance center.
How Data ONTAP uses continuous media scrubbing to prevent media errors
The purpose of the continuous media scrub is to detect and correct media errors in order to minimize the chance of storage system disruption due to a media error while a storage system is in degraded or reconstruction mode.
