Managing Systems and Workgroups: A Guide for HP-UX System Administrators

Administering a System: Managing Disks and Files
Managing Disks
Chapter 6 595
After you have made the LVM disk minimally bootable, the system can
be booted in maintenance mode using the -lm option of the hpux
command at the ISL> prompt. This causes the system to boot to
single-user state without LVM or dump but with access to the root file
system.
Maintenance mode is a special way to boot your system that bypasses the
normal LVM structures. It should be used only for problems that prevent
the system from otherwise booting. It is similar to single-user state in
that many of the processes that normally get started are not started, nor
are many of the system checks that are normally performed. It is
intended to allow you to boot your system long enough for you to repair
damage to your system’s LVM data structures typically using
vgcfgrestore which should then allow you to boot your system
normally.
The system must not be brought to multiuser state (that is, run-level 2 or
greater) when in LVM maintenance mode. Also, do not activate the root
volume group. Corruption of the root file system might result.
To exit LVM maintenance mode, use reboot -n.
When a Volume Group Will Not Activate Normally, volume groups
are automatically activated during system startup. Unless you
intentionally deactivate a volume group using vgchange, you will
probably not need to activate a volume group. However, LVM does
require that a quorum of disks in a volume group be available. During
bootup, LVM needs a quorum of more than half of the disks that are
included in the root volume group for activation of that volume group;
this means the majority of these disks must be online and in service.
Thus, if there are two disks in the root volume group, the more than half
requirement means that both will need to be available. To successfully
boot the system, LVM will require a quorum of one more than half of the
disks in the root volume group.
Another possible problem pertaining to activation of a volume group is a
missing or corrupted /etc/lvmtab file. You can use the vgscan (1M)
command to re-create the /etc/lvmtab file.
During run time, once a volume group is already active, if a disk fails or
is taken off line, quorum may become lost. This will occur if less than
half of the physical volumes defined for the volume group now remain
available. For example, if there are two disks in the volume group, the
loss of one would not cause a loss of quorum, as is the case when booting;
rather, both disks would need to become unavailable. If this happened,