Silicon Graphics InfiniteStorage 6120, User Manual

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Configuration Management
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3.2.4 Drive Rebuild
The InfiniteStorage 6120’s automatic drive failure recovery procedures ensure that absolute data
integrity is maintained while operating in degraded mode.
3.2.4.1 Full and Partial Rebuilds
Both full and partial (fractional) rebuilds are supported in the InfiniteStorage 6120. Rebuilds are
done at the storage pool level, not the virtual disk level. Partial rebuilds will reduce the time to return
the storage pool to full redundancy and can be controlled by adjustable time limit for each storage
pool. Permitted time limits are 0 (in which case partial rebuild is off) to 240 minutes. The timer will
begin when a disk in the storage pool is declared missing—if the disk reappears prior to the
expiration of the timer, a fractional rebuild will be done. Otherwise, the disk will be declared failed,
replaced by a spare and a full rebuild will begin to return the storage pool to full redundancy. The
default partial rebuild timer (Disk Timeout) setting is 10 minutes.
Under heavy write workloads, it is possible that the number of stripes that need to be rebuilt will
exceed the system’s internal limits prior to the timer expiration. When this happens, a full rebuild will
be started automatically instead of waiting for the partial rebuild timeout.
Use the
SHOW POOL <id> ALL_ATTRIBUTES
command to display the current Disk Timeout setting
(Figure 64)
.
To change the disk timeout setting, use this command:
SET POOL <id> DISK_TIMEOUT=<timeout>
where <timeout> is in the range of <0..240> minutes. The default setting is 10.
3.2.4.2 Sparing Policy
Each storage pool has a sparing policy that determines what happens when a physical disk within the
pool fails (or becomes inaccessible). In the event of a drive failure, the InfiniteStorage 6120 will
automatically initiate a drive rebuild if the sparing policy is set to automatic and a spare pool has been
assigned to the storage pool.
Use the
SHOW POOL <id> ALL_ATTRIBUTES
command to display the current settings
(Figure 65)
.
Figure 64. Show Pool All Attributes
RAID$ show pool 3 all
OID: 0x19b003
Type: STORAGE
Name: RAID5set
Chunk Size: 64KB (0x80 blocks)
Block Size: 0x200
RAID Type: RAID5
Free Raid5 Capacity: 2752512 MBs
Total Capacity: 3522560 MBs
UUID: 0x00
Global Spare Pool: 0x19bc0006
DiskTimeout(FRT): 10 minutes
....
Max VD Size: 2752512 MBs