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Create a Flash Pool local tier in ONTAP using SSD storage pool allocation units

Contributors netapp-thomi netapp-aherbin netapp-lenida netapp-dbagwell netapp-revathid netapp-ahibbard
PDFs

You can configure a Flash Pool local tier by adding one or more allocation units from an SSD storage pool to an existing HDD local tier.

Note Prior to ONTAP 9.7, System Manager uses the term aggregate to describe a local tier. Regardless of your ONTAP version, the ONTAP CLI uses the term aggregate. To learn more about local tiers, see Disks and local tiers.

Beginning with ONTAP 9.12.1, you can use the redesigned System Manager to create a Flash Pool local tier using storage pool allocation units.

Before you begin

  • You must have identified a valid local tier composed of HDDs to convert to a Flash Pool local tier.

  • You must have determined write-caching eligibility of the volumes associated with the local tier, and completed any required steps to resolve eligibility issues.

  • You must have created an SSD storage pool to provide the SSD cache to this Flash Pool local tier.

    Any allocation unit from the storage pool that you want to use must be owned by the same node that owns the Flash Pool local tier.

  • You must have determined how much cache you want to add to the local tier.

    You add cache to the local tier by allocation units. You can increase the size of the allocation units later by adding SSDs to the storage pool if there is room.

  • You must have determined the RAID type you want to use for the SSD cache.

    After you add a cache to the local tier from SSD storage pools, you cannot change the RAID type of the cache RAID groups.

  • You must have determined the maximum cache size for your system and determined that adding SSD cache to your local tier will not cause you to exceed it.

    You can see the amount of cache that will be added to the total cache size by using the storage pool show command.

  • You must have familiarized yourself with the configuration requirements for Flash Pool local tier.

About this task

If you want the RAID type of the cache to be different from that of the HDD RAID groups, you must specify the cache RAID type when you add the SSD capacity. After you add the SSD capacity to the local tier, you can no longer change the RAID type of the cache.

After you add an SSD cache to a local tier to create a Flash Pool local tier, you cannot remove the SSD cache to convert the local tier back to its original configuration.

System Manager

Beginning with ONTAP 9.12.1, you can use System Manager to add SSDs to an SSD storage pool.

Steps

  1. Click Storage > Tiers and select an existing local HDD storage tier.

  2. Click Menu options icon and select Add Flash Pool Cache.

  3. Select Use Storage Pools.

  4. Select a storage pool.

  5. Select a cache size and RAID configuration.

  6. Click Save.

  7. Locate the storage tier again and click Menu options icon.

  8. Select More Details and verify that the Flash Pool shows as Enabled.

CLI
Steps

  1. Mark the local tier as eligible to become a Flash Pool local tier:

    storage aggregate modify -aggregate aggr_name -hybrid-enabled true

    If this step does not succeed, determine write-caching eligibility for the target local tier.

  2. Show the available SSD storage pool allocation units:

    storage pool show-available-capacity

  3. Add the SSD capacity to the local tier:

    storage aggregate add aggr_name -storage-pool sp_name -allocation-units number_of_units

    If you want the RAID type of the cache to be different from that of the HDD RAID groups, you must change it when you enter this command by using the raidtype parameter.

    You do not need to specify a new RAID group; ONTAP automatically puts the SSD cache into separate RAID groups from the HDD RAID groups.

    You cannot set the RAID group size of the cache; it is determined by the number of SSDs in the storage pool.

    The cache is added to the local tier and the local tier is now a Flash Pool local tier. Each allocation unit added to the local tier becomes its own RAID group.

  4. Confirm the presence and size of the SSD cache:

    storage aggregate show aggregate_name

    The size of the cache is listed under Total Hybrid Cache Size.

Related information

NetApp Technical Report 4070: Flash Pool Design and Implementation Guide