NAME
vgcreate — create LVM volume group
SYNOPSIS
/usr/sbin/vgcreate
[-f]
[-A
autobackup]
[-x
extensibility]
[-e
max_pe]
[-l
max_lv]
[-p
max_pv]
[-s
pe_size]
[-g
pvg_name]
vg_name
pv_path ...
DESCRIPTION
The
vgcreate
command creates a new volume group.
vg_name
is a symbolic name for the volume group
and must be used in all references to it.
vg_name
is the path to a directory entry under
/dev
which must contain a character special file named
group.
Except for the
group
entry, the directory
vg_name
should be empty.
The
vg_name
directory and the
group
file have to be created by the user (see
lvm(7)).
vgcreate
leaves the volume group in an active state.
Before assigning a physical volume to a volume group,
the physical volume has to be created using the
pvcreate
command (see
pvcreate(1M)).
If
vgcreate
fails to install the first specified physical volume into the volume group,
the volume group is not created.
If, for any reason, one of the remaining specified physical volumes
cannot be installed into the volume group,
an error message is printed,
but the installation continues until the end of the list of physical volumes.
Options and Arguments
vgcreate
recognizes the following options and arguments:
- pv_path
The block device path name of a physical volume
that will be assigned to the new volume group.
You can specify physical volume links
(pv-links)
for a physical volume
providing
different paths that reference the same physical volume
in the
pv_path
list.
The order in which the paths are listed is important.
The first path becomes the
primary link
to the physical volume, the second becomes an
alternate link
to the physical volume.
The
primary link
is the default path used to access the physical volume. If the
primary link
becomes unavailable, LVM automatically switches to the
alternate link
to access the physical volume. Currently LVM supports
a maximum of 8 paths to a physical volume (7 alternate and
one primary).
- vg_name
The path name of a subdirectory of the
/dev
directory.
vg_name
must be empty except for a character special file named
group.
Typically, this directory name is in the form
/dev/vgNN,
where
NN
numbers sequentially from
00.
- -A autobackup
Set automatic backup for this invocation of this command.
autobackup
can have one of the following values:
- y
Automatically back up configuration changes made to the volume group.
This is the default.
After this command executes, the
vgcfgbackup
command (see
vgcfgbackup(1M))
is executed for the volume group.
- n
Do not back up configuration changes this time.
- -e max_pe
Set the maximum number of physical extents that can be allocated
from any of the physical volumes in the volume group.
The default value for
max_pe
is
1016.
However, if the size of any physical volume exceeds
1016
times the
pe_size,
the default value for
max_pe
is adjusted to match the physical volume size.
The maximum number of physical extents
can be a value in the range 1 to 65535.
- -f
This option will force a volume group to be created with a physical
volume which has alternate block(s) already allocated, (i.e. this
physical volume was not initialized using
pvcreate -f.)
This option should be used with extreme caution.
If the volume group to be created has a different physical extent
size, the alternate block(s) might be inside the user data
area. Potential data corruption could occur.
- -g pvg_name
Create a new physical volume group with the name
pvg_name.
All physical volumes specified in the
pv_path
parameter become a member of the newly created physical volume group.
The physical volume group information is stored in an ASCII file,
/etc/lvmpvg.
The file can be edited to create a physical volume group
instead of using the
vgcreate
command.
However, ensure that the physical volumes
to be used have already been installed in the volume group
prior to creating the physical volume group.
The physical volume group name must be unique within a volume group
although identical physical volume group names
can appear in different volume groups (see
lvmpvg(4)
for format details).
- -l max_lv
Set the maximum number of logical volumes
that the volume group is allowed to contain.
The default value for
max_lv
is
255.
The maximum number of logical volumes
can be a value in the range 1 to 255.
- -p max_pv
Set the maximum number of physical volumes
that the volume group is allowed to contain.
The default value for
max_pv
is
16.
The maximum number of physical volumes
can be a value in the range 1 to 255.
- -s pe_size
Sets the number of megabytes in each physical extent, where
pe_size
is expressed in units of megabytes (MB) in the range 1 to 256.
pe_size
must be equal to a power of 2 (1, 2, 4, 8, etc.).
The default value for
pe_size
is
4
(four megabytes).
- -x extensibility
Set the allocation permission for adding physical extents
on the physical volumes specified by the
pv_path
parameter.
extensibility
can have one of the following values:
- y
Allow allocation of additional physical extents on the physical volume.
This is the default.
- n
Prohibit allocation of additional physical extents on the physical volume.
Logical volumes residing on the physical volume
can still be accessed after the volume group has been activated by the
vgchange -a y
command.
EXTERNAL INFLUENCES
Environment Variables
LANG
determines the language in which messages are displayed.
If
LANG
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)).
EXAMPLES
Create a volume group named
/dev/vg00
containing two physical volumes with extent size set to 2 MB, from scratch.
First, create the directory
/dev/vg00
with the character special file called
group.
mkdir /dev/vg00
mknod /dev/vg00/group c 64 0x030000
The minor number for the
group
file should be unique among all the volume groups on the system.
It has the format
0xNN0000,
where
NN
runs from
00
to
09.
The maximum value of
NN
is controlled by the kernel tunable parameter
maxvgs.
Initialize the disks using
pvcreate(1M).
pvcreate /dev/rdsk/c1t0d0
pvcreate /dev/rdsk/c1t2d0
Create the volume group.
vgcreate -s 2 /dev/vg00 /dev/dsk/c1t0d0 /dev/dsk/c1t2d0
Create a volume group named
/dev/vg01
that can contain a maximum of three logical volumes,
with extent size set to 8 MB:
vgcreate -l 3 -s 8 /dev/vg01 /dev/dsk/c3t4d0
Create a volume group named
/dev/vg00
and a physical volume group named
PVG0
with two physical volumes:
vgcreate -g PVG0 /dev/vg00 /dev/dsk/c1t0d0 /dev/dsk/c2t0d0
Using the
PVLinks
feature to create a volume group named
/dev/vg00
with a physical volume which can be referenced by two different paths.
/dev/dsk/c3t0d0
and
/dev/dsk/c4t0d0
refer to the same physical volume, accessed via different controller hardware
paths.
In this example,
/dev/dsk/c3t0d0
becomes the
primary link
to the physical volume.
/dev/dsk/c4t0d0
becomes an
alternate link
to the physical volume.
vgcreate /dev/vg00 /dev/dsk/c3t0d0 /dev/dsk/c4t0d0
WARNINGS
It is not possible to create a volume group that contains both
HP-IB devices and devices using another type of interface.