HP-UX HB v13.00 Ch-13 - LVM

HP-UX Handbook – Rev 13.00 Page 97 (of 110)
Chapter 13 LVM
October 29, 2013
When trying to extend a logical volume through SAM, a lvextend error
is reported:
lvextend: Error detected when reading from file "/etc/lvmpvg".
The system does not have an /etc/lvmpvg file. Is it necessary to have this file?
RESOLUTION
Not every system needs to have an /etc/lvmpvg file. It is only necessary
if you want to have PVG's, or physical volume groups. They basically define
subgroups of physical volumes within a volume group.
In this case the allocation policy for the logical volume was set
to PVG-strict and distributed:
# lvdisplay /dev/vg03/lvol3
...
Allocation PVG-strict/distributed
With the allocation policy set to PVG-strict, lvextend will look for
the file /etc/lvmpvg and report an error if the file is not found.
The /etc/lvmpvg file was probably removed after the logical volume
was created.
In this case the logical volume resided on a VA array which already
striped the data. A decision was made to turn off the allocation policies
PVG-strict/distributed:
# lvchange -D n -s n /dev/vg03/lvol3
The lvextend command now succeeded.
For further information consult the man pages for lvcreate, lvchange
and lvmpvg.
2. PROBLEM LVM: Extending a Striped And Mirrored Logical Volume
When using lvextend (1M) to increase the size of logical volumes (lvols) which
are striped and mirrored, you must account for the allocation policy which by
default is assigned to those lvols. The allocation policy is that of
distributed allocation (lvextend -D) where only one free extent is allocated
from the first available physical volume. The next free extent is allocated
from the next available physical volume. Allocation of free extents proceeds in