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2. Basic Functions
RAID Functions
Note
Use drives that have the same capacity to configure RAID groups.
If a RAID group is configured with drives that have different capacities, all the drives in the RAID group are
recognized as having the same capacity as the drive with the smallest capacity in the RAID group and the
rest of the capacity in the drives that have a larger capacity cannot be used.
Table 9
shows the recommended number of drives that configure a RAID group.
Table 9
Recommended Number of Drives per RAID Group
RAID level
RAID1+0
RAID5
RAID5+0
RAID6
RAID6-FR
*1: D = Data, M = Mirror, P = Parity, HS = Hot Spare
Note
• Sequential access performance hardly varies with the number of drives for the RAID group.
• Random access performance tends to be proportional to the number of drives for the RAID group.
• Use of higher capacity drives will increase the time required for the drive rebuild process to complete.
• For RAID5, RAID5+0, and RAID6, ensure that a single RAID group is not being configured with too many
drives.
If the number of drives increases, the time to perform data restoration from parities and Rebuild/
Copyback when a drive fails also increases.
For details on the recommended number of drives, refer to
• The RAID level that can be registered in REC Disk Buffers is RAID1 or RAID1+0. For RAID1+0, the drive
configuration is 2D+2M or 4D+4M.
For details on the Thin Provisioning function and the RAID configurations that can be registered in Thin
Provisioning Pools, refer to
For details on the Flexible Tier function and the RAID configurations that can be registered in Flexible
Tier Pools, refer to
An assigned CM is allocated to each RAID group. For details, refer to
For the installation locations of the drives that configure the RAID group, refer to
Configuration" (page
Number of
Recommended number of drives (*1)
configuration drives
4 – 32
6(3D+3M), 8(4D+4M), 10(5D+5M)
3 – 16
3(2D+1P), 4(3D+1P), 5(4D+1P), 6(5D+1P), 7(6D+1P), 8(7D+1P)
4(3D+1P) ´ 2, 5(4D+1P) ´ 2, 6(5D+1P) ´ 2
6 – 32
5 – 16
5(3D+2P), 6(4D+2P), 7(5D+2P), 8(6D+2P)
17 ((6D+2P) ´2+1HS)
11 – 31
"Storage Capacity Virtualization" (page
"Automated Storage Tiering" (page
180).
Table
9.
50).
56).
"Assigned CMs" (page
26
107).
"Recommended RAID Group
Design Guide
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