HSG80 Array Controller V8.7 Command Line Interface Reference Guide
2–87
REDUCE
Removes member disk drives from mirrorsets and decreases the nominal number of
members in the mirrorsets.
This command does not put reduced members into the failedset (unlike the SET
mirrorset-name REMOVE=disk-name command). When using the REDUCE
command to take a snapshot of a striped mirrorset, you must reduce all mirrorsets with
one command. The CLONE utility does this automatically.
The nominal number of members in a mirrorset is determined by the number of
members assigned to the mirrorset with the SET mirrorset-name
MEMBERSHIP=number-of-members command or the ADD MIRRORSETS
mirrorset-name disk-name1 [disk-nameN] command—in other words, the number of
disks that the mirrorset originally contained before it was reduced. The actual number
of members contained in the mirrorset may be less than the nominal number of
members if:
•
A disk drive is not added back to the mirrorset.
•
A member remains removed from the mirrorset.
•
The mirrorset replacement policy switch NOPOLICY is specified with the SET
mirrorset-name command.
•
No spare disks exist.
The actual number of members in the mirrorset can never be greater than the nominal
number of members. The disks to be removed do not need to be members of the same
mirrorset. However, the disks must all be part of the same unit (for example, the same
striped mirrorset). When a disk is reduced from a mirrorset, the controller:
•
Flushes all of the unit's data from write-back data cache.
•
Pauses I/O to the unit.
•
Removes the specified disk(s).
•
Decreases the nominal number of members of the mirrorset(s) by the number of
disk(s) removed from the mirrorset(s).
•
Re-establishes I/O to the unit.
For each reduced mirrorset, there must be at least one remaining normal member after
the reduction. If this is not true for all of the disk-names specified, the mirrorset is not
reduced.
REDUCE