■
Recommended RAID Level
Select the appropriate RAID level according to the usage.
•
Recommended RAID levels are RAID1, RAID1+0, RAID5, RAID5+0, RAID6, and RAID6-FR.
•
When importance is placed upon read and write performance, a RAID1+0 configuration is recommended.
•
For read only file servers and backup servers, RAID5, RAID5+0, RAID6, or RAID6-FR can also be used for higher
efficiency. However, if the drive fails, note that data restoration from parities and rebuilding process may re-
sult in a loss in performance.
•
For SSDs, a RAID5 configuration or a fault tolerant enhanced RAID6 configuration is recommended because
SSDs operate much faster than other types of drive. For large capacity SSDs, using a RAID6-FR configuration,
which provides excellent performance for the rebuild process, is recommended.
•
Using a RAID6 or RAID6-FR configuration is recommended when Nearline SAS disks that have 6TB or more are
used. For details on the RAID levels that can be configured with Nearline SAS disks that have 6TB or more,
refer to
.
User Capacity (Logical Capacity)
User Capacity for Each RAID Level
The user capacity depends on the capacity of drives that configure a RAID group and the RAID level.
shows the formula for calculating the user capacity for each RAID level.
Table 4 Formula for Calculating User Capacity for Each RAID Level
RAID level
Formula for user capacity computation
RAID0
Drive capacity
´
Number of drives
RAID1
Drive capacity
´
Number of drives
¸
2
RAID1+0
Drive capacity
´
Number of drives
¸
2
RAID5
Drive capacity
´
(Number of drives - 1)
RAID5+0
Drive capacity
´
(Number of drives - 2)
RAID6
Drive capacity
´
(Number of drives - 2)
RAID6-FR
Drive capacity
´
(Number of drives - (2
´
N) - Number of hot spares) (*1)
*1: "N" is the number of RAID6 configuration sets. For example, if a RAID6 group is configured with "(3D+2P)
´
2+1HS", N is "2".
2. Basic Functions
RAID Functions
22
FUJITSU Storage ETERNUS DX500 S4/DX600 S4, ETERNUS DX500 S3/DX600 S3 Hybrid Storage Systems Design Guide (Basic)
Copyright 2019 FUJITSU LIMITED
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Содержание ETERNUS DX500 S3/DX600 S3
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