You can add disks or array LUNs to an aggregate so that it can provide more storage to its associated volumes.
Before you begin
- You must understand the requirement to add disks or array LUNs owned by the same system and pool
- For aggregates composed of disks, you must understand the following:
- Benefits of keeping your RAID groups homogeneous for disk size and speed
- Which types of disks can be used together
- Checksum rules when disks of more than one checksum type are in use
- How to ensure that the correct disks are added to the aggregate (the disk addition operation cannot be undone)
- How to add disks to aggregates from heterogeneous storage
- Minimum number of disks to add for best performance
- Number of hot spares you need to provide for protection against disk failures
- Requirements for adding disks from multi-disk carrier disk shelves
- Requirement to add storage to both plexes of a mirrored aggregate at the same time to ensure that the plexes are the same size and contain the same disk types
- If you are adding cache to a Flash Pool aggregate, the cache limit for your system model and how much cache you are adding towards the limit
About this task
This procedure should not be used for aggregates composed of root or data partitions.
Following these best practices when you add storage to an aggregate optimizes aggregate performance:
- Add a complete RAID group at one time.
The new RAID group does not have to be exactly the same size as the existing RAID groups, but it should not be less than one half the size of the existing RAID groups.
- If any small RAID groups exist already, you can bring them up to the size of the other RAID groups, as long as you add at least as many data drives as are already in the RAID group.
- Avoid adding a small number of drives to an existing RAID group.
Doing so results in the added disks being the target for a disproportionate percentage of new data, causing the new disks to become a performance bottleneck.
- Verify that appropriate spare disks or array LUNs are available for you to add: storage aggregate show-spare-disks -original-owner node_name
For disks, make sure that enough of the spares listed are of the correct type, size, speed, and checksum type for the target RAID group in the aggregate to which you are adding the disks.
- Add the disks or array LUNs: storage aggregate add-disks -aggregate aggr_name [-raidgroup raid_group_name] disks
If you are adding disks with a different checksum than the aggregate, as when creating a Flash Pool aggregate, or if you are adding disks to a mixed checksum aggregate, you must use the -checksumstyle parameter.
If you are adding disks to a Flash Pool aggregate, you must use the -disktype parameter to specify the disk type.
If you specify the -raidgroup parameter, the storage is added to the RAID group you specify. raid_group_name is the name that Data ONTAP gave to the group—for example, rg0. If you are adding SSDs to the SSD cache of a Flash Pool aggregate, you do not need to specify the RAID group name; the SSD RAID group is selected by default based on the type of the disks you are adding.
disks specifies the disks to be added in one of the following ways:
- -diskcount, usually further qualified by disk type or checksum type
- -disklist disk1 [disk2...]
If possible, you should use the diskcount option. Doing so allows Data ONTAP to optimize the disk selection for your configuration.
If you are adding disks to a mirrored aggregate and you are specifying disk names, you must also use the -mirror-disklist parameter.