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How does ONTAP trigger Spares Low Check?

Last Updated:

Applies to



Spares low checking is triggered under the following conditions:

  • At boot and takeover time.
  • By hourly check of spares by global status monitor.
  • When the M-host or a management applications invokes the aggr-check-spares-low Zapi.
  • When configuration change may result in new demand for spares, such as when an aggregate or plex is onlined.
  • Anytime the population of a spare pool changes.

There are two cases for change to population of a spare pool, addition and subtraction.

  • Addition: This includes the following cases:
    • Spare disks are added and/or assigned to a system. This includes case where disk is dynamically qualified, or finally completes initialization after initial failure.
    • An aggregate or plex is offlined and destroyed and its disks released to the spare pool.
    • Aggregate orphan disks are released to the spare pool.
    • A disk in broken pool is unfailed.
    • A disk is released from disk maintenance center with no trouble found.
    • Demotion of aggregate or RAID group type from RAID-DP to RAID4.
  • Subtraction: This includes the following cases:
    • Aggregate or plex creation.
    • Promotion of unmirrored to mirrored aggregate.
    • Addition of disks to an existing aggregate.
    • Promotion of aggregate or RAID group type from RAID4 to RAID-DP.
    • Allocation of replacement disk for reconstruction, disk copy operation for sick disk, disk replacement, or multi-disk carrier evacuation.
    • A spare disk is removed or failed.
    • A spare disk gets placed into disk maintenance center. This includes for maintenance testing, disk sanitization and disk recovery.

Additional Information

BUG 1209463 - Storage "spares low" condition reported infrequently 

With this change, "spares low" conditions are reported weekly, at minimum.


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