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
RAID group 1 RAID group 2
SAS
6
00GB
SAS
600GB
SAS
600GB
SAS
600GB
SAS
600GB
SSD
400GB
SSD
400GB
SSD
400GB
SSD
400GB
•
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), Advanced Format
support, interface 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 capaci-
ty in the RAID group and the rest of the capacity in the drives that have a larger capacity can-
not be used.
-
If a RAID group is configured with drives that have different rotational speeds, the perform-
ance of all of the drives in the RAID group is reduced to that of the drive with the lowest ro-
tational speed.
-
If a RAID group is configured with SSDs that have different interface speeds, the perform-
ance of all of the SSDs in the RAID group is reduced to that of the SSD with the lowest inter-
face 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.
-
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), be-
cause 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 16).
Table 7 shows the recommended number of drives that configure a RAID group.
Table 7 Number of Drives to Configure and the Recommended Number of Drives per RAID Group
RAID level
Number of configu-
ration drives
Recommended number of drives (*1)
RAID0 2 to 16 —
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
2. Basic Functions
RAID Functions
25
Fujitsu Storage ETERNUS DX100 S4/DX200 S4, ETERNUS DX100 S3/DX200 S3 Hybrid Storage Systems
Design Guide (Basic)
Copyright 2023 Fujitsu Limited
P3AM-7642-32ENZ0
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