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

HP-UX Handbook – Rev 13.00 Page 51 (of 110)
Chapter 13 LVM
October 29, 2013
- Check the /etc/lvmpvg file carefully whenever any PVs are added to, or removed
from, VGs. Amend manually if necessary.
Two other areas are worthy of discussion. These are the export/import of VGs, and the
question of JFS "hot spots".
When a VG is exported and imported, it is best to avoid the "-s" option if alternate links
are being used. This is because, whilst it simplifies the process, it will usually lead to a
situation where the imported VG has all its "primary" links to LVs down a single I/O
channel (the channel where they were first discovered by the "vgimport -s" process) -
and all the alternate links down another. This can be rectified by careful subsequent use
of vgreduce/vgextend commands (but NOT by use of pvchange which may only have a
temporary effect). However, it is better to specify a complete list of disks, in the correct
sequence to set up alternate links as desired, when the vgimport command is run. This
has the effect of making the import process much faster too. Whilst it can be tedious to
set up the command for import of a large VG in this way, it is helpful to note that a list of
disks can be established on the source system when the vgexport is carried out
(perhaps in preview mode) by using the "-f" option to capture a list of PVs in a file. With
appropriate editing, which will often be necessary to resolve differing channel numbers,
the target system can use same the list of disks with its vgimport command. It will be
necessary to amend /etc/lvmpvg manually after importing a VG (the entries for an
existing VG disappear when the VG is exported.
The JFS file system makes use of an "intent log" to improve performance and integrity.
This is held in the first extent of the LV in which a file system resides, and will tend to be
accessed more, on average, than the rest of the file system, if a substantial amount of
changes occur. It may therefore be worthwhile in some cases (for instance if monitoring
of I/O suggests an imbalance) to attempt to locate the first extent of each LV on a
different disk, to the degree that this is possible. However, the only easy way to manage
this process would be to amend the /etc/lvmpvg file, to change the sequence of the
PVs, in between each lvcreate command.
Offline Diagnostic Environment (ODE)
You need the OfflineDiagnostic (ODE) to be able to do HW troubleshooting in the case
the system is not able to boot. The ODE files are LIF files that should be installed in the
LIF volume on any bootable disk.
ODE is the LIF-LOAD product which is part of the OnlineDiag bundle:
# swlist OnlineDiag
# OnlineDiag B.11.11.15.13 HPUX 11.11 Support Tools Bundle, Dec 2004
OnlineDiag.Sup-Tool-Mgr B.11.11.15.13 Support Tools Manager for HPUX
systems