HP-UX System Administrator's Guide: Logical Volume Management (762803-001, March 2014)

command shows '???' for the physical volume if it is unavailable. The issue with this approach
is that it does not show precisely how many disks are unavailable. To ensure that multiple
simultaneous disk failures have not occurred, run vgdisplay to check the difference between
the number of active and number of current physical volumes. For example, a difference of
one means only one disk is failing.
A third option for determining which logical volumes are on the disk is to use the
vgcfgdisplay command, available from your HP support representative.
For each of the logical volumes affected, use lvdisplay to determine if the number of mirror
copies is greater than zero. This verifies that the logical volume is mirrored. For example:
# lvdisplay /dev/vg00/lvol1
--- Logical volumes ---
LV Name /dev/vg00/lvol1
VG Name /dev/vg00
LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 300
Current LE 75
Allocated PE 150
Stripes 0
Stripe Size (Kbytes) 0
Bad block off
Allocation strict/contiguous
IO Timeout (Seconds) default
The number of mirror copies is not zero; therefore, the logical volume is mirrored.
Use lvdisplay again to determine which logical extents are mapped onto the suspect disk,
and whether there is a current copy of that data on another disk. With the –v option,
lvdisplay shows every logical extent, its mapping to any physical extents, and the status
of those physical extents (stale or current).
This listing can be quite long, so use grep to confine the listing to the disk that is being
replaced. For example:
# lvdisplay -v /dev/vg00/lvol1 | grep –e /dev/disk/disk3 –e ’???’
00000 /dev/disk/disk3 00000 current /dev/disk/disk6 00000 current
00001 /dev/disk/disk3 00001 current /dev/disk/disk6 00001 current
00002 /dev/disk/disk3 00002 current /dev/disk/disk6 00002 current
00003 /dev/disk/disk3 00003 current /dev/disk/disk6 00003 current
00004 /dev/disk/disk3 00004 current /dev/disk/disk6 00004 current
00005 /dev/disk/disk3 00005 current /dev/disk/disk6 00005 current
...
In this example, all lvol1 physical extents on /dev/disk/disk3 have a current copy
elsewhere on the system, specifically on /dev/disk/disk6. If /dev/disk/disk3 was
unavailable when the volume group was activated, its column contains a ‘???’ instead of the
disk name.
NOTE: There might be an instance where you see that only the failed physical volume holds the
current copy of a given extent (and all other mirror copies of the logical volume hold the stale data
for that given extent), and LVM does not permit you to remove that physical volume from the volume
group. In this case, use the lvunstale command (available from your HP support representative)
to mark one of the mirror copies as “nonstale” for that given extent.
HP recommends you use the lvunstale tool with caution.
Based on the gathered information, choose the appropriate disk removal or disk replacement
procedure, detailed on the following pages. The possible scenarios are:
132 Troubleshooting LVM