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Operations
RAID functions
The unit provides RAID functions for the purpose of improving the reliability and availability.
The fault tolerance for the protection of data is different when writing and reading. RAID levels for each write and
read are listed in the following table.
≥ RAID 5 or 6 for write fault tolerance can be set from the application. In the factory default settings, the write
operation is enabled when the number of drive failure*
For more information about the settings, refer to the user manual for the application.
≥ The maximum transfer rate and the magazine capacity for writing are different depending on the RAID level
settings. For the maximum transfer rate and capacity for each RAID level, refer to "Specifications" ( 139).
Number of
drive failure = 1
Fault tolerance in
Number of
write
drive failure = 2
performance
Number of drive
failure
Number of
drive failure = 1
Fault tolerance in
Number of
read
drive failure = 2
performance
Number of drive
failure S 3
*1
Number of drives in the drive system for which the write/read performance is bad due to drive failure, media
defects in magazine, errors in the management information area, and access to lower redundancy space.
*2
The number of writable drive failures can be set to 0 or 1 in the application.
*3
The number of writable drive failures can be set to 0, 1 or 2 in the application.
Note
In order to improve reliability and availability, RAID 5 or 6 is recommended.
Various Functions
1
RAID 0
No write/Error report
S
3
No read/Error report
103
is 0 for RAID 5, the number of drive failure is 1 for RAID 6.
RAID Level
RAID 5
/
Writable*
2
Warning report
Readable/Warning report
RAID 6
/
Writable*
3
Warning report
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