Specifications

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Compaq HSG80 Array Controller ACS Version 8.4 Configuration and CLI Reference Guide
REDUCE
Removes member disk drives from mirrorsets and decreases the nominal number of
members in the mirrorsets.
Unlike the SET mirrorset-name REMOVE=disk-name command, the controller does
not put reduced members into the failedset. 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 MIRRORSET
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:
■ Pauses I/O to the unit
■ Flushes all of the unit’s data from write-back data cache
■ Removes the specified disks
■ Decreases the nominal number of members of the mirrorsets by the number of
disks removed from the mirrorsets.