Use SSD storage pools

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To enable SSDs to be shared by multiple Flash Pool aggregates, you can add the SSDs to a storage pool. After you add an SSD to a storage pool, you can no longer manage the SSD as a stand-alone entity. You must use the storage pool to assign or allocate the storage that is provided by the SSD.

You can create storage pools for a specific high-availability (HA) pair. Then, you can add allocation units from that storage pool to one or more Flash Pool aggregates that are owned by the same HA pair. Just as disks must be owned by the same node that owns an aggregate before the disks can be allocated to it, storage pools can provide storage only to the Flash Pool aggregates that are owned by one of the nodes that owns the storage pool.

If you have to increase the amount of Flash Pool cache on your system, you can add more SSDs to a storage pool, up to the maximum RAID group size for the RAID type of the Flash Pool caches that are using the storage pool. When you add an SSD to an existing storage pool, you increase the size of the storage pool’s allocation units, including any allocation units that are already allocated to a Flash Pool aggregate.

You can use only one spare SSD for a storage pool, so that if an SSD in that storage pool becomes unavailable, ONTAP can use the spare SSD to reconstruct the partitions of the malfunctioning SSD. You do not have to reserve any allocation units as spare capacity; ONTAP can use only a full, unpartitioned SSD as a spare for the SSDs in a storage pool.

After you add an SSD to a storage pool, you cannot remove the SSD, just as you cannot remove disks from an aggregate. If you want to use the SSDs in a storage pool as discrete drives again, you must destroy all of the Flash Pool aggregates to which the storage pool’s allocation units have been allocated, and then destroy the storage pool.