ONTAP 9 Manuals ( CA08871-402 )

Default RAID policies for local tiers (aggregates)

Either RAID-DP or RAID-TEC is the default RAID policy for all new local tiers (aggregates). The RAID policy determines the parity protection you have in the event of a disk failure.

RAID-DP provides double-parity protection in the event of a single or double disk failure. RAID-DP is the default RAID policy for the following local tier (aggregate) types:

  • All Flash local tiers

  • Flash Pool local tiers

  • Performance hard disk drive (HDD) local tiers

RAID-TEC is supported on all disk types and all platforms, including ETERNUS AX. Local tiers that contain larger disks have a higher possibility of concurrent disk failures. RAID-TEC helps to mitigate this risk by providing triple-parity protection so that your data can survive up to three simultaneous disk failures. RAID-TEC is the default RAID policy for capacity HDD local tiers with disks that are 6 TB or larger.

Each RAID policy type requires a minimum number of disks:

  • RAID-DP: minimum of 5 disks

  • RAID-TEC: minimum of 7 disks

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