Important Note: If you have RAID-TEC aggregates, if you add an allocation unit to your Flash Pool it will default to RAID-TEC and cannot be changed (would make more sense if it defaulted to RAID-DP for SSDs.)
In the following scenario, we have a NetApp ONTAP 8.3.2
HA-Pair, with one DS2246 shelf half populated with 12 SSDs, and 4 pre-existing SATA
data aggregates (2 per node). We will create a storage pool using 11 disks
(leaving one SSD spare across the HA-Pair*), and use this one storage pool to
hybrid-enable the 4 data aggregates.
Note: Most of this
information can be got from the Physical
Storage Management Guide.
The following commands:
- Determine the names of the spare SSDs
- Create the storage pool (simulate)
- Create the storage pool
- Show the storage pool
- Hybrid enable aggregate (x4)
- Add 1 storage pool allocation unit** to the aggregate (x4)
- Rename the aggregate to reflect that it is now hybrid
SATA (x4)
storage
aggregate show-spare-disk -disk-type SSD
storage
pool create -storage-pool SP1 -disk-list disk1,disk2,...,disk11 -simulate true
storage
pool create -storage-pool SP1 -disk-list disk1,disk2,...,disk11
storage
pool show -storage-pool SP1
storage
aggregate modify -aggregate N1_sata_1 -hybrid-enabled true
storage
aggregate modify -aggregate N1_sata_2 -hybrid-enabled true
storage
aggregate modify -aggregate N2_sata_1 -hybrid-enabled true
storage
aggregate modify -aggregate N2_sata_2 -hybrid-enabled true
storage
aggregate add N1_sata_1 -storage-pool SP1 -allocation-units 1
storage
aggregate add N1_sata_2 -storage-pool SP1 -allocation-units 1
storage
aggregate add N2_sata_1 -storage-pool SP1 -allocation-units 1
storage
aggregate add N2_sata_2 -storage-pool SP1 -allocation-units 1
aggr
rename -aggr N1_sata_1 -newname N1_hata_1
aggr
rename -aggr N1_sata_2 -newname N1_hata_2
aggr
rename -aggr N2_sata_1 -newname N2_hata_1
aggr
rename -aggr N2_sata_2 -newname N2_hata_2
That’s it!
Notes:
* “When a storage
pool is used to provision cache, and each node has at least one allocation unit
from the storage pool, only 1 spare SSD is needed for the HA pair. When
dedicated SSDs are used for Flash Pool cache, each node needs a hot spare.
There is no global spare for non-partitioned, non-shared drives.”
** Storage from an
SSD storage pool is divided into 4 allocation units - hence one storage pool
can be shared by up to 4 aggregates. In a HA-pair, initially each node has 2
allocation units - these allocation units can be reassigned.
Other notes:
i) Remember, once
you’ve added a storage pool allocation unit (or 2/3/4) to an aggregate, you can’t
delete the storage pool without first deleting the data aggregate.
ii) It is easy to
add an SSD disk to a storage pool (storage pool add), but you cannot remove
SSDs from the storage pool without deleting it.
iii) SSDs in a
storage pool are partitioned into 4 partitions per disk, hence the 4 allocation
units. This also allows the storage pool to be shared by RAID-4 and RAID-DP HDD
aggregates as in the diagram below.
Image: SSD Storage
Pool providing cache to two Flash Pool aggregates
iv) For flash pool
throughput metrics use statistics
cache flash-pool show
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