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How to determine the number of disks or disk partitions required for an aggregate

You must have enough disks or disk partitions in your aggregate to meet system and business requirements. You should also have the recommended number of hot spare disks or hot spare disk partitions to minimize the potential of data loss.

Root-data partitioning is enabled by default on certain configurations. Systems with root-data partitioning enabled use disk partitions to create aggregates. Systems that do not have root-data or root-data-data partitioning enabled use unpartitioned disks.

You must have enough disks or disk partitions to meet the minimum number required for your RAID policy and enough to meet your minimum capacity requirements.
Note
In ONTAP, the usable space of the drive is less than the physical capacity of the drive. You can find the maximum number of drives in a RAID group allowed on the Lenovo Press site for a DM model. The minimum number of disks for RAID-DP Is 5 (3 data disks + 2 parity disks) and the minimum number of disks for RAID-TEC is 7 (4 data disks + 3 parity disks). You can use the storage aggregate show-spare-disks command to find the usable space of a specific disk.

In addition to the number of disks or disk partitions necessary to create your RAID group and meet your capacity requirements, you should also have the minimum number of hot spare disks or hot spare disk partitions recommended for your aggregate:

  • For all flash aggregates, you should have a minimum of one hot spare disk or disk partition.

  • For non-flash homogenous aggregates, you should have a minimum of two hot spare disks or disk partitions.

  • For Flash Pool aggregates, you should have a minimum of two hot spare disks or disk partitions for each disk type.