Red Hat GLOBAL FILE SYSTEM 5.0, Руководство администратора

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The
contiguous
policy requires that new extents are adjacent to existing extents. If there are
sufficient free extents to satisfy an allocation request but a
normal
allocation policy would not
use them, the
anywhere
allocation policy will, even if that reduces performance by placing two
stripes on the same physical volume. The
cling
policy places new extents on the same
physical volume as existing extents in the same stripe of the logical volume. These policies can
be changed using the
vgchange
command.
In general, allocation policies other than
normal
are required only in special cases where you
need to specify unusual or nonstandard extent allocation.
LVM volume groups and underlying logical volumes are included in the device special file
directory tree in the
/dev
directory with the following layout:
/dev/vg/lv/
For example, if you create two volume groups
myvg1
and
myvg2
, each with three logical
volumes named
lvo1
,
lvo2
, and
lvo3
, this create six device special files:
/dev/myvg1/lv01
/dev/myvg1/lv02
/dev/myvg1/lv03
/dev/myvg2/lv01
/dev/myvg2/lv02
/dev/myvg2/lv03
The maximum device size with LVM is 8 Exabytes on 64-bit CPUs.
3.2. Adding Physical Volumes to a Volume Group
To add additional physical volumes to an existing volume group, use the
vgextend
command.
The
vgextend
command increases a volume group's capacity by adding one or more free
physical volumes.
The following command adds the physical volume
/dev/sdf1
to the volume group
vg1
.
vgextend vg1 /dev/sdf1
3.3. Displaying Volume Groups
There are two commands you can use to display properties of LVM volume groups:
vgs
and
vgdisplay
.
The
vgscan
command will also display the volume groups, although its primary purpose is to
scan all the disks for volume groups and rebuild the LVM cache file. For information on the
Adding Physical Volumes to a Volume
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