User`s guide

6.11.2 Mirrorset SET Commands and Qualifiers
Use the SET mirrorset-container-name command and one of its qualifiers to
change the characteristics of a mirrorset as listed:
CLI> SET MIRR1 MEMBERSHIP= number-of-members
CLI> SET MIRR1 REPLACE= disk-device-name
CLI> SET MIRR1 REMOVE= disk-device-name
CLI> SET MIRR1 POLICY= policy-type
CLI> SET MIRR1 READ_SOURCE= read-source
CLI> SET MIRR1 COPY= copy_speed
The following are the SET mirrorset-container-name qualifiers and descriptions
for using them:
• MEMBERSHIP= number-of-members—Allows you to increase or decrease the
nominal membership of a mirrorset to the number you specify in number-of-
members. If the mirrorset membership is increased, and automatic sparing is
turned on, the mirrorset automatically brings in spares until the new number
of members is attained, or until no more suitable spares are available.
Membership cannot be decrease below the number of active members.
Remove members first, then reduce membership.
• REPLACE= disk-device-name—Allows you to add mirrorset members to an
existing mirrorset. There are two conditions for using this qualifier:
– The replacement policy must be set to NOPOLICY.
– The mirrorset must be missing at least one member.
If these two conditions are met, the physical device is added to the mirrorset
you named. The nominal number of members does not change.
• REMOVE= disk-device-name—Allows you to remove a member from an
existing mirrorset. If the physical disk you specify is not a member of the
mirrorset you specified, or if the mirrorset will not have a NORMAL or
NORMALIZING member after the disk is removed, an error is reported
and no action is taken. If the disk removal is successful, the removed disk
is added to the failedset, and a new disk member is auto-spared into the
mirrorset (if applicable). The nominal number of members in the mirrorset
does not change. If for some reason the auto-sparing does not take place, the
mirrorset automatically adds the spare when an acceptable spare becomes
available or when the replacement policy changes.
• REDUCE disk-device-name1 [disk-device-nameN]—Allows you to remove
members from an existing mirrorset. Refer to Section 6.11.4.
• POLICY= policy-type—Allows you to set the desired automatic replacement
policy for disks that fail out of a mirrorset.
• BEST_FIT gives highest priority to finding a replacement device within
the spareset that closely matches the sizes of the remaining members of
the mirrorset. If several spareset members are the same size, the best
performance algorithm is used to determine the best device to add to the
mirrorset.
• BEST_PERFORMANCE (default) gives the highest priority to finding
a replacement device that is on a different port than any of the current
mirrorset members. If several spareset members are on different ports,
then the best fit algorithm is used to determine the best device to add to
the mirrorset.
Working with RAID Arrays 6–23