Chapitre 3. Managing LVM volume groups
A volume group (VG) is a collection of physical volumes (PVs), which creates a pool of disk space out of which logical volumes (LVs) can be allocated.
Within a volume group, the disk space available for allocation is divided into units of a fixed-size called extents. An extent is the smallest unit of space that can be allocated. Within a physical volume, extents are referred to as physical extents.
A logical volume is allocated into logical extents of the same size as the physical extents. The extent size is therefore the same for all logical volumes in the volume group. The volume group maps the logical extents to physical extents.
3.1. Creating LVM volume group
This procedure describes how to create an LVM volume group (VG) myvg, by using the /dev/vdb1 and /dev/vdb2 physical volumes.
Conditions préalables
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The
lvm2package is installed. - One or more physical volumes are created. For more information about creating physical volumes, see Creating LVM physical volume.
Procédure
Create a volume group:
# vgcreate myvg /dev/vdb1 /dev/vdb2 Volume group "myvg" successfully created.
This creates a VG with the name of myvg. The PVs /dev/vdb1 and /dev/vdb2 are the base storage level for the myvg VG .
View the created volume groups by using any one of the following commands according to your requirement:
The
vgscommand provides volume group information in a configurable form, displaying one line per volume groups:# vgs VG #PV #LV #SN Attr VSize VFree myvg 2 0 0 wz-n 159.99g 159.99gThe
vgdisplaycommand displays volume group properties such as size, extents, number of physical volumes, and other options in a fixed form. The following example shows the output of thevgdisplaycommand for the volume group myvg. To display all existing volume groups, do not specify a volume group:# vgdisplay myvg --- Volume group --- VG Name myvg System ID Format lvm2 Metadata Areas 4 Metadata Sequence No 6 VG Access read/write [..]
The
vgscancommand scans all supported LVM block devices in the system for volume group:# vgscan Found volume group "myvg" using metadata type lvm2
Optional: Increase a volume group’s capacity by adding one or more free physical volumes:
# vgextend myvg /dev/vdb3 Physical volume "/dev/vdb3" successfully created. Volume group "myvg" successfully extended
Optional: Rename an existing volume group:
# vgrename myvg myvg1 Volume group "myvg" successfully renamed to "myvg1"
Ressources supplémentaires
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vgcreate(8),vgextend(8),vgdisplay(8),vgs(8),vgscan(8),vgrename(8), andlvm(8)man pages
