To create a backup of the main data on my raid system for removal offsite, I'm using 2 2tb drives. I attach them to a utility system and create a Logical Volume group which fills both. the current set I'm using was created by installing a system and allowing it to create the LVM spanning both drives. As such one of the drives has a few gb of space at the front with a root boot partition, which is a primary partition not in the LVM. On the original system once booted, the LVM had the root, home and another boot partiton inside the LVM.
In order to mount this one needs to install some tools on the system. I found a page advising to install two gui's which are quite useful.
One is a KDE utility KVPM. It or the other utility drags in the lvm tools. Another one is system-config-lvm.
http://ossnotebook.blogspot.com/2009/02/lvm-tools-in-ubuntu-jaunty.html
The command line tools allow installation of the lvm. The lvm scans all disks for logical volume groups. These are marked with unique ID's from when they are created. All are shown via the commands in the lvm command.
vgdisplay shows information on the volume group:
--- Volume group ---
VG Name vg_apex2
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 1
Max PV 0
Cur PV 2
Act PV 2
VG Size 3.64 TiB
PE Size 32.00 MiB
Total PE 119216
Alloc PE / Size 119216 / 3.64 TiB
Free PE / Size 0 / 0
VG UUID ISZMQ4-BNdD-J9Cf-f72S-GgiI-TslM-w8sSqm
pvs shows the physical information
lvm> pvs
PV VG Fmt Attr PSize PFree
/dev/sdb2 vg_apex2 lvm2 a- 1.82t 0
/dev/sdc1 vg_apex2 lvm2 a- 1.82t 0
pvdisplay shows more information on the volumes
lvm> pvdisplay
--- Physical volume ---
PV Name /dev/sdb2
VG Name vg_apex2
PV Size 1.82 TiB / not usable 28.00 MiB
Allocatable yes (but full)
PE Size 32.00 MiB
Total PE 59600
Free PE 0
Allocated PE 59600
PV UUID cdqH1r-Z873-mmC4-XZpY-Vsrc-YXd1-PwF8VS
--- Physical volume ---
PV Name /dev/sdc1
VG Name vg_apex2
PV Size 1.82 TiB / not usable 16.00 MiB
Allocatable yes (but full)
PE Size 32.00 MiB
Total PE 59616
Free PE 0
Allocated PE 59616
PV UUID hJyfL3-RbkR-SxbM-ffHk-q70G-1iu9-6r58yx
The next thing that has to be performed is to make the volume group visible to the system. The vgchange -ay makes the volume group active. Once it is active /dev/vg* will be visible and the members of each vg directory are the file systems. After the vgchange is performed, all the need be done is to mount the volume group, such as;
mount /dev/vg_apex2/lv_home /apex2
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