Determine the number of disks or disk partitions required for a local tier (aggregate)
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You must have enough disks or disk partitions in your local tier (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 local tiers. Systems that do not have root-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.
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In ONTAP, the usable space of the drive is less than the physical capacity of the drive. You can find the usable space of a specific drive and the minimum number of disks or disk partitions required for each RAID policy in the Hardware Universe. |
Determine usable space of a specific disk
The procedure you follow depends on the interface you use—System Manager or the CLI:
Use System Manager to determine usable space of disks
Perform the following steps to view the usable size of a disk:
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Go to Storage > Tiers
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Click
next to the name of the local tier. -
Select the Disk Information tab.
Use the CLI to determine usable space of disks
Perform the following step to view the usable size of a disk:
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Display spare disk information:
storage aggregate show-spare-disks
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:
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For all flash aggregates, you should have a minimum of one hot spare disk or disk partition.
The AFF C190 defaults to no spare drive. This exception is fully supported.
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For non-flash homogenous aggregates, you should have a minimum of two hot spare disks or disk partitions.
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For SSD storage pools, you should have a minimum of one hot spare disk for each HA pair.
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For Flash Pool aggregates, you should have a minimum of two spare disks for each HA pair. You can find more information on the supported RAID policies for Flash Pool aggregates in the Hardware Universe.
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To support the use of the Maintenance Center and to avoid issues caused by multiple concurrent disk failures, you should have a minimum of four hot spares in multi-disk carriers.