Monitoring Disk Resources

Disk Monitor Reference

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.

MirrorDisk/UX supports up to 3-way mirroring, so there 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 isn’t.

Note that when you configure mirroring in LVM, it lists 0 mirrors to mean you have one copy of the data. Likewise, 2 mirrors mean you have 3 copies of the data (one original plus 2 mirrors). The disk monitor is monitoring all copies of data, and therefore counts the “original” as part of the total number of copies.

Table 2-5

Interpreting Logical Volume Copies

 

 

 

 

 

 

Resource Name

vg/vgName/lv/copies/lvName

 

 

 

 

 

 

Condition

Interpretation

 

 

 

 

 

 

0

No copies, 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 available; if the data is not mirrored,

 

 

 

then all physical extents are fine, if 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

 

 

 

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.

 

 

 

 

When configuring requests from the SAM interface, a wildcard (*) may be used 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.

Chapter 2

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HP HA s Software manual Logical Volume Number of Copies, Interpreting Logical Volume Copies