Saturday, 7 January 2017

1 HA-Pair, 1 Storage Pool, and 4 Flash Pool Aggregates

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!

* “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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