Fujitsu Eternus DX80 S2 - Figure 4.7 Example of a RAID Group; RAID Groups; Table 4.2 Recommended Number of Drives Per RAID Group

Chapter 4 System Configuration
4.2 RAID Groups
ETERNUS DX80 S2/DX90 S2 Disk storage system Overview
Copyright 2013 FUJITSU LIMITED P3AM-4812-11ENZ0
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4.2 RAID Groups
This section explains RAID groups.
A RAID group is a group of drives. It is a unit that configures RAID. Multiple RAID groups with the same RAID
level or multiple RAID groups with different RAID levels can be set together in the ETERNUS DX Disk storage
system. After a RAID group is created, RAID levels can be changed and drives can be added.
The same size drives (2.5", 3.5") and the same kind of drives (SAS, Nearline SAS, SLC type SSD, MLC type SSD,
or SED) must be used to configure a RAID group.
Figure 4.7 Example of a RAID group
Table 4.2
shows the recommended number of drives that configure a RAID group.
Table 4.2 Recommended number of drives per RAID group
*1: D = Data, M = Mirror, P = Parity
RAID level Number of configuration drives Recommended number of drives (*1)
RAID1 2 2(1D+1M)
RAID1+0 4 to 32 4(2D+2M), 6(3D+3M), 8(4D+4M), 10(5D+5M)
RAID5 3 to 16 3(2D+1P), 4(3D+1P), 5(4D+1P), 6(5D+1P)
RAID5+0 6 to 32 3(2D+1P) × 2, 4(3D+1P) × 2, 5(4D+1P) × 2, 6(5D+1P) × 2
RAID6 5 to 16 5(3D+2P), 6(4D+2P), 7(5D+2P)
• 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.
• The higher the number of drives in a RAID5, RAID5+0, or RAID6 configuration, the longer the period of
time for data restoration and rebuilding processes from parities.
• To use the Thin Provisioning function or the Flexible Tier function, the drive area of the virtual volume is
managed using a pool.
The following table shows the RAID configurations that can be registered in a Thin Provisioning Pool or a
Flexible Tier Pool.
RAID group 1 RAID group 2
SAS
600GB
SAS
600GB
SAS
600GB
SAS
600GB
SAS
600GB
SSD
200GB
SSD
200GB
SSD
200GB
SSD
200GB