How does ONTAP trigger Spares Low Check?

ONTAP

Spares low checking is triggered under the following conditions:

At boot and takeover time.
By hourly check of spares by global status monitor.
- Mon Nov 20 14:59:00 +0900 [Node01: monitor: monitor.globalStatus.nonCritical:error]: Disk on adapter 0b, shelf 0, bay 8, failing. There are not enough spare disks.
- When does "monitor.globalStatus.xxx" get notified?
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.

BUG 1209463 - Storage "spares low" condition reported infrequently

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