Using High Availability Monitors (June 2003)

Monitoring Disk Resources
HA Disk Monitor Reference
Chapter 2 35
Logical Volume Number of Copies
The logical volume number of copies is most useful to monitor in a
mirrored disk configuration. It tells you how many copies of the data are
available. The HA Disk Monitor monitors all copies of data, and
therefore counts the “original” as part of the total number of copies.
MirrorDisk/UX supports up to 3-way mirroring, so the range can be from
0 to 3 copies (see Table 2-5). In a RAID configuration that is not mirrored
using LVM, the only possible number is 0 or 1; either the data is
accessible or it is not.
When you first configure mirroring in LVM, it lists 0 mirrors, meaning
you have only the original copy of the data. Likewise, 2 mirrors mean you
have one original plus 2 mirrored copies.
When configuring requests from the SAM interface, use a wildcard (*) in
place of lvName to request status for all logical volumes in a volume
group.
If you split off mirrors from your mirrored configuration, you will see the
number of copies reduced by 1 when the split mirror is created.
Table 2-5 Interpreting Logical Volume Copies
Resource Name: vg/ vgName /lv/copies/ lvName
Condition Interpretation
0 No additional copies, (only the original copy), either physical
parts of the disk array have problems, the lv is inactive, or a
physical extent is stale or unavailable.
1 One complete copy of data is available. If the data is not
mirrored, then all physical extents are fine. If the data is
mirrored, all other copies have problems.
2 Two complete copies of data are available. If the data is
two-way mirrored, then all physical disks are up and data is
available. If the data is 3-way mirrored, at least one logical
extent has a missing or stale physical extent.
3 All copies of a 3-way mirror are available.