ATTO Technology Diamond Storage Array S-Class - Manual (Page 70)

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ATTO Technology Inc. Diamond Storage Array Installation and Operation Manual
6.4 RAID Level 5
RAID Level 5 increases reliability while using fewer disks than mirroring by employing parity
redundancy. Distributed parity on multiple drives provides the redundancy to rebuild a failed drive from
the remaining good drives.
CAUTION CAUTION
Selecting RAID configuration causes all
previous drive data on the Diamond
Storage Array to be erased. Make sure all
information is backed up before
configuring RAID groups.
In RAID Level 5, parity data is added to the
transmitted data at one end of the transaction, then
the parity data is checked at the other end to make
sure the transmission has not had any errors.
In the Diamond Storage Array, transmitted data
with the added parity data is striped across disk
drives. A hardware XOR engine computes parity,
thus alleviating software processing during reads
and writes.
The array uses parity declustering, a special case
of RAID Level 5. Parity information is spread
across each LUN, not concentrated on one drive
or sled.
When you initially set up RAID groups using the
QuickRAID command, groups are synchronized
automatically because there is no pre-existing
data on the drives. However, drives may display
as “degraded, and you need to set all LUNs to OK
status. Refer to
Rebuilding RAID Level Configurations
on page 63.
Configuring a fully-populated array
You may set up a fully-populated Diamond (12
sleds) into one, two, three or four RAID Level 5
groups, with or without hot spare sleds, using the
QuickRAID 5 command.
To set up RAID Level 5 groups
1 Connect to Diamond Storage Array services via
the RS-232 port or the optional Ethernet
management services card (refer to
Accessing
the Array on page 17). You should now be in the
CLI.
2 Continue with the CLI or access the RAID page
of the ExpressNAV interface (refer to
ATTO
ExpressNAV: Browser-based Interface on page 25).
Note
Because the ExpressNAV pages take you
through this process easily, the following
instructions are based on the CLI commands.
Use these instructions as a guide in
ExpressNAV.
3 Decide how many RAID Level 5 groups you
want (1, 2, 3 or 4)..
4 Type set QuickRAID5 [0|1|2|3|4]
0 returns the array to JBOD
5 Type SaveConfiguration Restart to save the
RAID Level 5 configuration.
6 A Ready prompt displays. You must zero all
drives and parity to make all RAID Level 5
drives coherent. Type RAID5ClearData al
l
CAUTION CAUTION
This is a destructive operation: all
information stored on these drives is lost.
DO NOT interrupt power until the
RAID5ClearData operation has completed
(three to six hours).
7 Information displays on the screen while the
array updates NVRAM ending with a Ready
*.
8 Type SaveConfiguration.
9 Type FirmwareRestart to reboot the array.
10 Reboot the host computer connected via Fibre
Channel or SCSI to the array.
11 The array is now configured. To verify the
configuration, type DriveInfo. If any sleds are
missing, the sled slots are reported as
offline .
To set up one RAID Level 5 group with one Hot
Spare sled
1 Connect to Diamond Storage Array services
(refer
Accessing the Array on page 17) and use
the Command Line Interface or enter ATTO
ExpressNAV browser interface Advanced CLI
Configuration page.