Figure 8 Example Of A Raid Group; Table 7 Recommended Number Of Drives Per Raid Group - Fujitsu ETERNUS DX500 S4/DX600 S4 Design Manual

2. Basic Functions
RAID Functions
The same size drives (2.5", 3.5") and the same kind of drives (SAS disks, Nearline SAS disks, SSDs, or SEDs) must
be used to configure a RAID group.

Figure 8 Example of a RAID Group

SAS SAS
600GB 600GB
SAS disks and Nearline SAS disks can be installed together in the same group. Note that SAS disks and Near-
•
line SAS disks cannot be installed with SSDs or SEDs.
Use drives that have the same size, capacity, rotational speed (for disks), Advanced Format support, inter-
•
face speed (for SSDs), and drive enclosure transfer speed (for SSDs) 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.
If a RAID group is configured with SSDs that have different interface speeds, the performance of all of the
-
SSDs in the RAID group is reduced to that of the SSD with the lowest interface 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 to-
gether in the same RAID group.
When a RAID group is configured with SSDs in both the high-density drive enclosure (6Gbit/s), and the
-
3.5" type drive enclosure or the high-density drive enclosure (12Gbit/s), because the interface speed of
the high-density drive enclosure (6Gbit/s) is 6Gbit/s, all of the SSDs in the RAID group operate at 6Gbit/s.
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 7 shows the recommended number of drives that configure a RAID group.

Table 7 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
FUJITSU Storage ETERNUS DX500 S4/DX600 S4, ETERNUS DX500 S3/DX600 S3 Hybrid Storage Systems Design Guide (Basic)
SAS SAS
600GB 600GB
RAID group 1
16).
Number of configura-
Recommended number of drives (*1)
tion drives
2 2(1D+1M)
4 to 32 4(2D+2M), 6(3D+3M), 8(4D+4M), 10(5D+5M)
3 to 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 to 32
5 to 16 5(3D+2P), 6(4D+2P), 7(5D+2P)
17 ((6D+2P) ´2+1HS)
11 to 31
Copyright 2019 FUJITSU LIMITED
SAS
SSD
600GB
400GB
25
SSD SSD SSD
400GB 400GB 400GB
RAID group 2
P3AM-7722-25ENZ0