User guide

Chapter 1 Overview
> 1.2 Configuration
ETERNUS DX60/DX80/DX90 Disk storage system User Guide
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Copyright 2010 FUJITSU LIMITED
P3AM-3042-06ENZ0
Table 1.2 Formula for calculating user capacity for each RAID level
*1: Actual number of disks can be installed depend on the models.
■ Reliability, performance, capacity for each RAID level
Table 1.3 shows the comparison result of reliability, performance, capacity for each RAID level.
Table 1.3 User capacity for each RAID level
*1: Performance may differ according to the number of disks and the processing method from the host.
■ Recommended RAID level
Select the appropriate RAID level according to the usage.
• Recommended RAID level is RAID1, RAID1+0, RAID5, RAID5+0 and RAID6.
• For read and write performance, RAID1+0 configuration is recommended.
• For read only file servers and backup servers, RAID5, RAID5+0, or RAID6 can also be used.
However, if the disk fails, note that data restoration from parities and rebuilding process may
result in a loss in performance.
RAID level Number of disks (*1) Formula for user capacity computation
RAID0 2 to 16 Disk capacity × Number of disks
RAID1 2 Disk capacity × Number of disks/2
RAID1+0 4 to 32 Disk capacity × Number of disks/2
RAID5 3 to 16
Disk capacity ×
(Number of disks - 1)
RAID5+0 6 to 32
Disk capacity ×
(Number of disks - 2)
RAID6 5 to 16
Disk capacity ×
(Number of disks - 2)
RAID level Reliability Performance
(Writing speed) (*1)
Capacity
RAID0 Bad Very Good Very Good
RAID1 Good Good Not Bad
RAID1+0 Good Very Good Not Bad
RAID5 Good Good Good
RAID5+0 Good Good Good
RAID6 Very Good Good Good