LVM (Logical Volume Manager) is a tool in Linux which can help you manage disk drives and partition. Usually it being used in server/computer whereby you can easily re-size the partition, creating snapshots backup, combined all hard disk to be run under one partition and many more.
In this case, I already have logical volume “/dev/mapper/VolGroup00-LogVol00″ mounted as “/” partition in the server but the disk space is too small which is 50GB. I want to expand it to 170GB with another 120GB hard disk combine together. The new hard disk already plugged in the server and detected by the system. So we are going to do this online without downtime. Variables as below:
OS: CentOS 5.6 64bit LV name: /dev/mapper/VolGroup00-LogVol00 New HD: /dev/sdb (120GB)
1. Make sure that you have logical volume mapped to your “/” partition. If you are using default CentOS partitioning during installation, you should see something like below:
[root@centos ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup00-LogVol00 47G 3.2G 43.8G 8% / /dev/sda1 99M 13M 81M 14% /boot tmpfs 249M 0 249M 0% /dev/shm
2. Check whether new hard disk has been detected on the system or not. It should be /dev/sdb:
root@centos ~]# fdisk -l Disk /dev/sda: 53.6 GB, 53687091200 bytes 255 heads, 63 sectors/track, 6527 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 6527 52323705 8e Linux LVM Disk /dev/sdb: 128.8 GB, 128849018880 bytes 255 heads, 63 sectors/track, 15665 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Disk /dev/sdb doesn't contain a valid partition table
3. This new hard disk does not have partition table yet. So we need to create one using fdisk:
[root@centos ~]# fdisk /dev/sdb ...... Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 1 First cylinder (1-15665, default 1): Using default value 1 Last cylinder or +size or +sizeM or +sizeK (1-15665, default 15665): Using default value 15665 Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table.
[notice type=”information” title=”Info” tag=”h4″]The sequence I press on the keyboard is: n > p > 1 > Enter > Enter > w > Enter[/notice]
4. Lets check the partition for all hard disk again. Make sure /dev/sdb1 exist and you got something like below:
[root@centos ~]# fdisk -l Disk /dev/sda: 53.6 GB, 53687091200 bytes 255 heads, 63 sectors/track, 6527 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 6527 52323705 8e Linux LVM Disk /dev/sdb: 128.8 GB, 128849018880 bytes 255 heads, 63 sectors/track, 15665 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 1 15665 125829081 83 Linux
5. Lets create Physical Volume from the Linux partition we have in /dev/sdb1:
[root@centos ~]# pvcreate /dev/sdb1 Physical volume "/dev/sdb1" successfully created
6. If you notice above that we want to extend “/” partition which hold by volume group “VolGroup00“. Lets extend the volume group to the newly created Physical Volume:
[root@centos ~]# vgextend VolGroup00 /dev/sdb1 Volume group "VolGroup00" successfully extended
7. Then, we need to extend the Logical Volume for VolGroup00 which is LogVol00:
[root@centos ~]# lvextend /dev/VolGroup00/LogVol00 /dev/sdb1 Extending logical volume LogVol00 to 167.88 GB Logical volume LogVol00 successfully resized
8. We have expand the partition but not the file system. So we need to tell the ext3 file system to use all newly added space in the partition /dev/VolGroup00/LogVol00:
[root@centos ~]# resize2fs /dev/VolGroup00/LogVol00 resize2fs 1.39 (29-May-2006) Filesystem at /dev/VolGroup00/LogVol00 is mounted on /; on-line resizing required Performing an on-line resize of /dev/VolGroup00/LogVol00 to 44007424 (4k) blocks. The filesystem on /dev/VolGroup00/LogVol00 is now 44007424 blocks long.
9. Done. Lets check our new “/” partition disk space. It has combined with new 120GB hard disk with total space of 163GB:
[root@centos ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/VolGroup00-LogVol00 163G 2.9G 152G 2% / /dev/sda1 99M 13M 81M 14% /boot tmpfs 501M 0 501M 0% /dev/shm
Thanks LVM for this great tool!
