Figure 3 Example Of A Raid Group; Figure 49 Rec; Table 15 Recommended Number Of Drives Per Raid Group - Fujitsu ETERNUS DX S5 Series Design Manual

2. Basic Functions
RAID Functions
The same size drives (2.5" or 3.5"), the same kind of drives (SAS disks, Nearline SAS disks, SSDs, or SEDs), and
the same capacity drives must be used to configure a RAID group.
Figure 3 Example of a RAID Group
SAS SAS
600GB 600GB
Note
• SAS disks and Nearline SAS disks can be installed together in the same group. Note that SAS disks and
Nearline SAS disks cannot be installed with SSDs or SEDs.
• Use drives that have the same size, capacity, rotational speed (for disks), and Advanced Format support
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.
- If a RAID group is configured with drives that have different rotational speeds, the performance of all
of the drives in the RAID group is reduced to that of the drive with the lowest rotational speed.
- 3.5" SAS disks are handled as being the same size type as the drives for high-density drive enclosures.
For example, 3.5" Nearline SAS disks and Nearline SAS disks for high-density drive enclosures can exist
together in the same RAID group.
• For details on the RAID levels that can be configured with Nearline SAS disks that have 6TB or more,
refer to "Supported RAID" (page
Table 15 shows the recommended number of drives that configure a RAID group.
Table 15 Recommended Number of Drives per RAID Group
RAID level
RAID1
RAID1+0
RAID5
RAID5+0
RAID6
RAID6-FR
*1: D = Data, M = Mirror, P = Parity, HS = Hot Spare
SAS SAS
600GB 600GB
RAID group 1
33).
Number of
Recommended number of drives (*1)
configuration drives
2 2(1D+1M)
4 – 32 4(2D+2M), 6(3D+3M), 8(4D+4M), 10(5D+5M)
3 – 16 3(2D+1P), 4(3D+1P), 5(4D+1P), 6(5D+1P)
3(2D+1P) ´ 2, 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)
17 ((6D+2P) ´2+1HS)
11 – 31
SAS SSD
600GB 960GB
38
SSD SSD SSD
960GB 960GB 960GB
RAID group 2
Design Guide