vgmodify(1M)vgmodify(1M)NAMEvgmodify - handle physical volume size changes and modify configuration
parameters of an existing LVM volume group
SYNOPSISvgmodify Options for Volume Groups Version 1.0
max_pe] max_lv] max_pv] vg_name
bootable max_pe] max_lv] max_pv] vg_name pv_path ...
max_pe] max_lv] max_pv] vg_name [pv_path...]
vg_name
bootable vg_name pv_path ...
vg_name [pv_path...]
dlc_size vg_name pv_path
vg_name
bootable vg_name pv_path ...
vg_conf_path vg_name pv_path ...
vgmodify Options for Activated Volume Groups Version 2.0 and Higher
vg_name [pv_path...]
dlc_size vg_name pv_path
vg_size vg_name
DESCRIPTION
The command allows the user to modify an existing volume group
(vg_name).
The modifications that can perform depend on the version of the volume
group and whether or not the volume group is activated.
The following changes can be performed for volume groups version 1.0:
· Detect and handle physical volume size changes.
If the volume group is activated, the option of must be specified to
take advantage of increased physical volume sizes.
If the volume group is deactivated, will implicitly handle increased
physical volume sizes.
· Prepare a physical volume for a LUN contraction (dlc_size setting).
· Modify the maximum number of physical extents that can be allocated
per physical volume (max_pe setting) (see vgcreate(1M)
· Modify the maximum number of physical volumes that the volume group
can contain (max_pv setting) (see vgcreate(1M)
· Modify the maximum number of logical volumes that the volume group
can contain (max_lv setting) (see vgcreate(1M)
· Change a physical volume type from boot to non-boot or vice versa
(see pvcreate(1M) Note that making a physical volume non-bootable
will increase the space available on that device for LVM configura‐
tion data. However, even a single bootable physical volume in the
volume group will restrict the max_pv and max_pe settings available.
For volume groups version 1.0, all the physical volumes associated with
the volume group must be available for the command to succeed. Also,
if the command is interrupted before it completes, recovery steps might
be required. See the section for details.
The following changes can be performed for volume groups version 2.0:
· Detect and handle physical volume size changes.
The option must be specified to take advantage of increased physical
volume size.
· Prepare a physical volume for a LUN contraction (dlc_size setting).
· Modify the maximum volume group size (vg_size setting) (see vgcre‐
ate(1M)
For volume groups version 2.0 and higher, is allowed only when the vol‐
ume group is in an activated state.
Options and Arguments
The command recognizes the following arguments and options:
vg_name The path name of a volume group.
pv_path The character (raw) device path name of a
physical volume. Refer to the and options
for the physical volume list usage.
Perform volume group reconfiguration when the volume group is
activated. This option is required if the
volume group is activated. The command will
fail if this option is used on a deactivated
volume group. For version 1.0 volume groups,
this option is ignored when used with the
and options.
Applicable to volume groups version 1.0 only.
Make the physical volumes specified in the
pv_paths list bootable or non-bootable. The
option is mutually exclusive with the and
options.
bootable can have one of the following val‐
ues:
Change pv_path list from non-bootable to
bootable.
Change pv_path list from bootable to non-
bootable.
See the description of the option in pvcre‐
ate(1M).
Making a physical volume non-bootable will
increase the space available on that device
for LVM configuration data. However to
fully use that space all the physical vol‐
umes in the volume group should be non-
bootable. A single bootable physical volume
in the volume group will restrict the avail‐
able configuration settings.
A physical volume can only be made bootable
if either all extents on it are unused or it
was previously converted from a bootable
device and the space is still unused.
If a physical volume is being made bootable
then use and to complete the process (see
lvlnboot(1M) and mkboot(1M)).
Prepare the physical volume for LUN contraction to
dlc_size. Exactly one pv_path must be spec‐
ified with the option. The option cannot be
used in conjunction with any other option
except for and
The unit for dlc_size is specified as a suf‐
fix. The recognized values for the suffix
are (megabytes), (gigabytes), (terabytes),
and (petabytes). If no suffix is supplied,
then (megabytes) is assumed. A dlc_size of
512 terabytes would be specified as 512t.
Only whole numbers are accepted.
The size should be at least 1 megabyte, and
no greater than a volume group version
dependent maximum; use the command to deter‐
mine the maximum size for a physical volume.
Reconfigure an activated volume group to take advantage of phys‐
ical volume
size increase. This option must be used
with the option. The option cannot be used
in conjunction with the and options.
If pv_path is not specified, will account
for size increase of all physical volumes in
the volume group.
Applicable to volume groups version 1.0 only.
Set the maximum number of physical extents
that can be allocated from any of the physi‐
cal volumes in the volume group (see vgcre‐
ate(1M)
The maximum number of physical extents can
range from the current highest physical
extent in use on any physical volume in the
volume group (1 if none in use) up to 65535.
The option displays a table of possible
max_pe values for vg_name.
Applicable to volume groups version 1.0 only.
Set the maximum number of logical volumes
that the volume group is allowed to contain
(see vgcreate(1M)
The maximum number of logical volumes can
range from the current highest logical vol‐
ume number in use (1 if none in use) to 255.
Note that changing this value has little
impact on the size of the LVM configuration
data.
Applicable to volume groups version 1.0 only.
Allow renumbering of physical extents on
physical volumes. This only applies to
physical volumes that have allocated
extents. By default, physical extent num‐
bers will be unchanged by
Renumbering physical extents changes the
allocation of the first physical extent, if
it is free, from user to LVM configuration
data and vice-versa. This will often have a
considerable impact on the space available
for the LVM configuration data on each phys‐
ical volume and, therefore, the possible
settings for the volume group parameters.
No user data is moved during that process,
only the LVM numbering of physical extents
changes.
When the first extent is being reallocated
from user to LVM configuration data, the
physical extent numbers are decreased. This
will only occur if the first extent is free.
For example a logical volume using physical
extents 10 to 20 from a physical volume that
has its first extent reallocated to LVM con‐
figuration data will use the physical
extents 9 to 19 after the modification.
User data is not moved.
When the first extent is being reallocated
from LVM configuration to user data, the
physical extent numbers are increased. For
example a logical volume using physical
extents 10 to 20 from a physical volume that
has its first extent re-allocated to user
data will use the physical extents 11 to 21
after the modification. User data is not
moved.
Not all configurations allow renumbering.
If this is the case then an error will be
reported and a recommendation to rerun with‐
out the option will be given.
Applicable to volume groups version 1.0 only.
Optimize the volume group settings. The
maximum number of extents and physical vol‐
umes are adjusted upwards, where possible,
to make full use of the space reserved on
each physical volume for the LVM configura‐
tion data.
This option cannot be used in conjunction
with or
Note: If renumbering is necessary, then
rerun with and rather than
Applicable to volume groups version 1.0 only.
Set the maximum number of physical volumes
that the volume group is allowed to contain
(see vgcreate(1M) The maximum number of
physical volumes can range from the current
number of physical volumes in the volume
group to 255.
The option displays a table of possible
max_pv values for vg_name.
Applicable to volume groups version 1.0 only.
Recover from a previous that either failed
or was interrupted. The configuration in
the vg_conf_file will be restored onto the
pv_path list given.
Report the effect of the other options being used.
No changes will be made to the volume group.
This option can be used on an active volume
group.
Only applicable to volume groups version 2.0 and higher.
Changes the maximum size of the volume
group. The unit for vg_size is specified as
a suffix. The recognized values for the suf‐
fix are (megabytes), (gigabytes), (ter‐
abytes), and (petabytes). If no suffix is
supplied, then (megabytes) is assumed. A
vg_size of 512 terabytes would be specified
as 512t. Only whole numbers are accepted.
Applicable to volume groups version 1.0 only.
Produce a table showing the optimal possible
settings (max_pe, max_pv, and maximum disk
size) for the volume group.
This option can be used with and without to
see a complete list of possible optimal set‐
tings. In certain cases the optimal set‐
tings will not be influenced by the extent
renumbering and a suitable message will then
be reported.
Where adjacent max_pv values allow the same
highest max_pe, only the highest max_pv is
displayed; therefore, there may be gaps in
the table. It is still possible to set a
lower max_pv or max_pe than shown in the ta‐
ble but some of the LVM configuration space
will not be used.
is normally used to obtain the arguments for
future command and/or options.
Applicable to volume groups version 1.0 only.
Verbose. Be verbose in reporting.
Remarks for Volume Groups Version 1.0
· This command can be run on volume groups version 1.0 that are deac‐
tivated or activated in standalone or exclusive mode only. The com‐
mand will fail on volume groups activated in shared mode.
· If of a volume group is interrupted while it is committing the con‐
figuration changes onto the disks, it may be necessary to re-apply
the configuration to all the physical volumes. The script or the
option must be used to accomplish this. For a deactivated volume
group, to apply the new configuration using the restore script enter
the following:
Or to apply the old/original configuration, enter the following:
For an activated volume group, the configuration file used with the
restore script, or with the option, should correspond to the config‐
uration of the volume group before was run.
· The root/boot volume group must be booted into maintenance mode
before making changes (see boot(1M)).
· If a volume group has any cluster lock physical volume, all recon‐
figuration and disk resize operations will fail, with one exception.
A disk resize operation on a physical volume in an activated volume
group will succeed if that specific physical volume does not have a
cluster lock.
· To expand the LVM configuration data to its maximum size, it may be
necessary to reallocate the first physical extent from each physical
volume from user to LVM configuration data. This will only be pos‐
sible if the first extent is made free (see pvmove(1M)) and PE
renumbering is enabled via the option.
· The LVM configuration data size is limited to the volume group
extent size. Therefore, a maximum of one physical extent from each
physical volume can be reallocated from user data regardless of how
many times is used on the volume group.
· The attributes of an file can be viewed using the option of (see
vgcfgrestore(1M)).
· To take advantage of a physical volume size increase, it may be nec‐
essary to run to increase the maximum number of physical extents for
the volume group. For a deactivated volume group, the command will
implicitly consider the physical volume size increase. But for an
activated volume group, the option should be used for to consider
the physical volume size increase.
· In general, a smaller number of physical volumes allows a larger
number of physical extents. Likewise, a larger number of physical
volumes constraints to a smaller number of physical extents.
· For a deactivated volume group, the detection of physical volume
size changes (LUN size expansion or contraction) is automatic, with
the handling taking place unless the or options have been used.
· For an activated volume group, the detection of a physical volume
size increase (LUN size expansion) is not automatic. Instead, the
option should be used for to detect and handle the physical volume
size increase.
· When used with the option, the option reports if the physical volume
can be prepared for contraction to the specified size. If not, it
displays the number of extents that need to be freed up on physical
volume before it can be prepared for contraction to the specified
size. In addition, it reports the smallest size to which the physi‐
cal volume can be prepared for contraction without performing any
operations on it, and the smallest size to which the physical volume
can be prepared for contraction after compacting all the allocated
physical extents on it by moving them up.
· The changing of physical volume type (boot to non-boot or vice
verse) is selected via the option and by specifying a list of physi‐
cal volumes. Otherwise, no physical volume type changes are per‐
formed.
· For an activated volume group, the and the options are mutually
exclusive, since the physical volume list for the option is the list
of the physical volumes to change from boot to non-boot or vice
versa. The physical volume list for the and options is the list of
physical volumes to consider for increase and decrease in disk size,
respectively.
Remarks for Volume Groups Version 2.0 and Higher
· This command can be run on volume groups version 2.0 and higher that
are activated in standalone or exclusive mode. It can also run on
volume groups activated in shared mode if they are 2.1 or higher. In
the case of a shared volume group, the command must be issued on the
server and the daemon must be running on all the nodes sharing the
volume group. See lvmpud(1M).
· If is interrupted while it is reconfiguring the physical volumes, or
if the command fails, then the volume group is left in a consistent
state (no special recovery is needed). To retry the operation, run
the command with the desired options, and LVM will continue with the
reconfiguration.
· will fail if the volume group has a cluster lock physical volume.
· The detection of a physical volume size increase (LUN size expan‐
sion) is not automatic. Instead, the option should be used to detect
and handle the physical volume size increase.
· When used with the option, the option reports if the physical volume
can be prepared for contraction to the specified size. If not, it
displays the number of extents that need to be freed up on physical
volume before it can be prepared for contraction to the specified
size. In addition, it reports the smallest size to which the physi‐
cal volume can be prepared for contraction by removing all free
extents on the physical volume.
· When used with the option, the option reports if the volume can be
reconfigured to the specified volume group size. If not, it displays
the number of extents that need to be freed up on each physical vol‐
ume before the volume group size can be reconfigured. In addition it
reports the largest volume group size possible for each physical
volume, and the largest volume group size possible when removing
free extents.
EXTERNAL INFLUENCES
Environment Variables
determines the language in which messages are displayed.
If is not specified or is null, it defaults to "C" (see lang(5)).
If any internationalization variable contains an invalid setting, all
internationalization variables default to "C" (see environ(5)).
RETURN VALUE
returns one of the following values:
Successful completion.
Error condition occurred.
EXAMPLES
Examples For a Volume Group Version 1.0
The volume group version 1.0 is deactivated in the following examples.
Review the effect of setting a maximum of 6 physical volumes in the
volume group:
Set a maximum of 4000 physical extents per physical volume and a maxi‐
mum of 50 physical volumes, and take advantage of extent renumbering if
possible:
Show a table of optimal possible settings for the volume group:
Show a table of optimal possible settings for the volume group taking
advantage of extent renumbering if possible:
Show a table of optimal possible settings for the volume group, making
the physical volume non-bootable:
Review (do not change) the effect of choosing a maximum of 16 physical
volumes, 8000 physical extents per physical volume, while making non-
bootable (these values were selected from the table above) and be ver‐
bose:
Apply the settings just reviewed:
If the command is interrupted, restore the new configuration to all
physical volumes in the volume group by entering:
The volume group version 1.0 is activated in the following examples.
Add extents to the physical volume that has been expanded by dynamic
LUN expansion:
Use the review option to determine if the physical volume can be pre‐
pared for LUN contraction to 4000 MB:
Apply the LUN contraction setting that was just reviewed:
Examples For a Volume Group Version 2.0 or Higher
The volume group version 2.0 is activated in the following examples.
Add extents to the physical volume that has been expanded by dynamic
LUN expansion:
Prepare physical volume for LUN contraction to size 4000 MB:
Use the review option to determine if the volume group size can be
increased to 256 terabytes:
Apply the volume group size increase that was just reviewed:
Increase the maximum size of the volume group to 256 terabytes, and
also check if any physical volumes have been expanded by a dynamic LUN
expansion:
Decrease the volume group size to 2 terabytes, to free up extents on
the physical volumes:
WARNINGS
· Applicable to volume group version 1.0 only. Changing the type of a
bootable physical volume will prevent booting from this device and,
therefore, may create an unbootable system.
· Do not restore a physical volume from a backup file produced prior
to the latest changes. Doing so will result in attempts to attach
the device to the volume group failing and may lead to activation
failures. If there is any doubt about the configuration in the
file, use to view the settings in the file.
· Applicable to volume group version 1.0 only. If the command is
interrupted prior to completing its operation, then restoration to
all physical volumes in the volume group may be required. Use the
restore script to accomplish this (see the section for more informa‐
tion).
FILES
Holds the latest (new) configuration for the volume group.
If completes successfully, this file contains the same new configu‐
ration as If was interrupted, this file contains the previous
(old) configuration.
A script created by
before making any update, to be used if the command is inter‐
rupted while committing the configuration changes to the physi‐
cal volumes. See the section for its usage.
SEE ALSOboot(1M), lvlnboot(1M), lvmpud(1M), mkboot(1M), pvcreate(1M),
pvmove(1M), vgcfgbackup(1M), vgcfgrestore(1M), vgchange(1M), vgcre‐
ate(1M), vgdisplay(1M), vgextend(1M), vgreduce(1M), lvm(7).
vgmodify(1M)
