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

3.4.7.1 Handling Size Increases
From the LUN Side:
Disk arrays typically allow a LUN to be resized. If the volume group is activated during size
increase, this is known as Dynamic LUN Expansion (DLE). If you increase the size of a LUN, follow
these steps to incorporate the additional space into the volume group:
1. Increase the LUN size using the instructions for the array.
2. Verify that the LUN is expanded by running the diskinfo command.
From the LVM Side (for Version 1.0 Volume Groups):
Do the following for Version 1.0 volume groups.
1. Run vgmodify to detect any physical volume size changes. It also reports whether all of the
space can be made available to the volume group.
2. If vgmodify reports that the maximum number of physical extents per physical volume
(max_pe) is too small to accommodate the new size, use vgmodify with the -t and -n
options to determine a new value for max_pe, as described in “Modifying volume group
parameters” (page 61).
3. Review the values by running vgmodify with the new settings and the -r option.
4. Deactivate the volume group, if needed.
TIP: Beginning with the September 2008 Update, you can use vgmodify to recognize and
accommodate size increases without deactivating the volume group. For more information,
see vgmodify(1M).
5. Commit any new value of max_pe and update the physical volume information by running
vgmodify without the -r option.
6. If needed, activate the volume group. To verify that the increased space is available, run the
vgdisplay and pvdisplay commands.
From the LVM Side (for Version 2.x Volume Groups):
Do the following for Version 2.x volume groups.
NOTE: Beginning with the September 2009 Update, the vgmodify also supports Version 2.x
volume groups, but the volume groups must be in active mode to run vgmodify. For more
information, see vgmodify(1M).
If the LUN for a physical volume was dynamically expanded using an array utility, the vgmodify
-E option can be used to make available the new space for user data. After the physical volume
is reconfigured, you can expand logical volumes with lvextend, or you can create new logical
volumes with lvcreate.
The extra space added to a physical volume through an array utility can also be used for additional
LVM configuration data when increasing the maximum VG size through the vgmodify -S option
(see “Modifying volume group parameters” (page 61)). The vgmodify –E and –S options can
also be used together to perform DLE and to increase maximum VG size increase in a single step.
To handle dynamic LUN expansion for a PV in a Version 2.x volume group, follow these steps:
1. Use vgdisplay -v to determine which PV in the volume group require expansion and
decide how much each LUN needs to be expanded. This decision can be based on which
logical volumes need to grow and which PVs they can reside on. This decision can also be
based on whether or not the DLE is being performed as part of increasing the maximum VG
size. See the “Modifying volume group parameters” (page 61) section for a description for
DLE in combination with increasing VG size limit.
2. Use the vgmodify -r (review) option to verify which physical volumes require reconfiguration
for DLE and to check if the reconfiguration will yield the desired result. If no PVs are specified
3.4 Moving and Reconfiguring Your Disks 81