Quick Steps
- Creating hard drive space into logical volumes.
- Since physical volumes cannot span over more than one drives.
- /boot partition cannot be a lvm because the partition cannot be read by the boot loader
- /boot should be on a separate partitions. - ext3
- lvm2 uses the device mapper driver in the kernel 2.6
First create PV -physical volume, then create volume group-VG, and then the logical volume-LV.
How To Create LVM Logical Volume Manager And Work With With LVM
- physical volumes = /dev/hdb1
- volume groups= used to create logical volumes (example 'mydatavg')
- logical volumes= (example /dev/mydatavg/myvol)
In LVM, Volume Groups (VGs) are split up into logical volumes (LVs)
Check image at http://www.lea-linux.org/cached/printable=yes/index/Leapro-pro_sys-lvm.html
[root@galileo ~]# fdisk -l
Disk /dev/sda: 80.0 GB, 80032038912 bytes
255 heads, 63 sectors/track, 9730 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 25 200781 83 Linux
/dev/sda2 26 156 1052257+ 82 Linux swap
/dev/sda3 157 9730 76903155 83 Linux
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*
Initialize sda3 as a physical volume
[root@galileo ~]# pvcreate /dev/sda3
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pvcreate - initialize a disk or partition for use by LVM
[root@galileo ~]# pvcreate /dev/sdb
[root@galileo ~]# pvcreate /dev/sdc
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Once initialised the partitions, or drives, we will create a volume group.
[root@galileo ~]#vgcreate mydatavg /dev/sda3
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vgcreate - create a volume group
Here "mydatavg" is the name of the volume group.
Single volume spanning two disks.
[root@galileo ~]#vgcreate mydatavg /dev/sdb /dev/sdc
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output of vgscan
[root@galileo ~]# vgscan
Reading all physical volumes. This may take a while...
Found volume group "mydatavg" using metadata type lvm2
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- vgscan scans all SCSI, (E)IDE disks, multiple devices and a bunch of
other disk devices in the system looking for LVM physical volumes and
volume groups.
Create logical volumes which we can mount and actually use.
[root@galileo ~]#lvcreate -n myvol --size 1g mydatavg
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This command creates a volume of size 1Gb with the name myvol hosted on the LVM volume group mydatavg.
The logical volume will now be accessible via= /dev/mydatavg/myvol
Formatted and mounted just like any other partition.
[root@galileo ~]# mkfs.ext3 /dev/mydatavg/myvol
[root@galileo ~]# mkdir /home/lvmmount
[root@galileo ~]# mount /dev/mydatavg/myvolt /home/lvmmount
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lvdisplay - display attributes of a logical volume
[root@galileo ~]# lvdisplay
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vgscan - scan all disks for volume groups and rebuild caches
How to Resize the volume= /dev/mydatavg/myvolt
[root@galileo ~]# umount /home/lvmmount
[root@galileo ~]# lvextend -L+1g dev/mydatavg/myvolt
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lvextend - extend the size of a logical volume
-L, --size [+]LogicalVolumeSize[kKmMgGtT]
Extend or set the logical volume size in units in units of
megabytes.
- check lvdisplay again...but ext3 filesystem on it has stayed unchanged.
- We need to resize the filesystem to actually fill the volume:
[root@galileo ~]# e2fsck -f /dev/mydatavg/myvolt
-f Force checking even if the file system seems clean.
root@lappy:~# resize2fs /dev/mydatavg/myvolt
resize2fs - ext2/ext3 file system resizer
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How to Remove LVM
lvremove - remove a logical volume
[root@galileo ~]# lvremove /dev/mydatavg/myvolt
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NAME
- If partition is to be mounted at boot-time you should update your /etc/fstab
/dev/mydatavg/myvolt /home/lvmmount ext3 noatime 0 2
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Running pvdisplay will allow you to see which physical volume(s) make up your volume group.
Check /etc/lvm/ directory.
Video - Detailed instructions on creating and extending a LVM volume on Red Hat Enterprise Linux 6.
http://www.youtube.com/watch?v=OhsR1bNd3kE