IBM N Series Hardware Manual page 162

consist of four concurrent disk failures followed by a bad block or bit error before
reconstruction is completed.
Creating RAID-DP aggregates and traditional volumes
To create an aggregate or traditional volume with RAID-DP–based RAID groups, select that
option in FilerView when provisioning storage. You can also add the –t raid_dp switch to the
traditional aggr or vol create command on the command-line interface. The command-line
interface syntax is [vol | aggr] create name –t raid_dp X, with X representing the number of
disks the traditional volume or aggregate contains. If the type of RAID group is not specified,
Data ONTAP automatically uses the default RAID group type. The default RAID group type
used, either RAID-DP or RAID4, depends on the platform and disk that are used.
The output shown in Figure 10-19 from the vol status command shows a four-disk RAID-DP
RAID group for a traditional volume named test. The second parity disk for diagonal parity is
dparity
denoted as .
Figure 10-19 Volume status command output of aggregate
Converting existing aggregates and traditional volumes to RAID-DP
Existing aggregates and traditional volumes can be easily converted to RAID-DP by using the
command [aggr | vol] options name raidtype raid_dp. Figure 10-20 shows the example
itso volume as a traditional RAID4 volume.
Figure 10-20 vol status command showing 'itso" volume as traditional RAID4 volume
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IBM System Storage N series Hardware Guide