Wednesday, October 7, 2009

resize a mounted lvm-managed disk in linux

I have found many overly-complex and incorrect and/or unnecessary instructions all over the web. So, I made this reference for me, but it may work well for you too. I typically use RHEL4/5 in my data center implementations, so these steps cover lvm managed disk space (which is decent for a simple LAMP stack).

I tend to do the following a lot in vmware products (workstation/esx/esxi).

First, check and note the size of your disks and partitions in your target vm.

[root@host]# df -h

Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
5.8G 665M 4.9G 12% /
/dev/sda1 99M 9.1M 85M 10% /boot
none 506M 0 506M 0% /dev/shm

[root@host]# sfdisk -s
/dev/sda: 8385898
/dev/sda1: 104391
/dev/sda2: 8281507
/dev/dm-0: 6160384
/dev/dm-1: 2031616


Then, go into the settings of your vm (e.g. through the vi client) and either add another virtual hard disk or increase the size of the existing disk. In my case i simply extended the existing virtual disk from 8G to 16G.

Reboot.

Check to see that the size of /dev/sda has increased.


[root@host]# sfdisk -s
/dev/sda: 16777216
/dev/sda1: 104391
/dev/sda2: 8281507
/dev/dm-0: 6160384
/dev/dm-1: 2031616

[root@host]# sfdisk -l

Disk /dev/sda: 2088 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

Device Boot Start End #cyls #blocks Id System
/dev/sda1 * 0+ 12 13- 104391 83 Linux
/dev/sda2 13 1043 1031 8281507+ 8e Linux LVM
/dev/sda3 0 - 0 0 0 Empty
/dev/sda4 0 - 0 0 0 Empty


/* If you increased the size of your existing disk, its probably easiest to boot from the gparted-live disk and create a new primary partition in the newly free space, format ext3. */
wget http://downloads.sourceforge.net/project/gparted/gparted-live-stable/0.4.6-1/gparted-live-0.4.6-1.iso?use_mirror=softlayer

reboot

/* check for /dev/sda3, your new parition */

[root@host]# sfdisk -s
/dev/sda: 16777216
/dev/sda1: 104391
/dev/sda2: 8281507
/dev/sda3: 8385930
/dev/dm-0: 6160384
/dev/dm-1: 2031616


/* create the lvm pv reference */

[root@host]# pvcreate /dev/sda3


/* extend the lvm vg reference */

[root@host]# vgextend VolGroup00 /dev/sda3


/* note the free space for your upcoming `lvextend` command */

[root@host]# vgdisplay

--- Volume group ---
VG Name VolGroup00
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 2
Act PV 2
VG Size 15.84 GB
PE Size 32.00 MB
Total PE 507
Alloc PE / Size 250 / 7.81 GB
Free PE / Size 257 / 8.03 GB
VG UUID L7woQB-ymCv-NeWL-i47M-b5Ua-fOHQ-hM0DXI


/* extend the lvm vg reference */

[root@host]# lvextend -L+8.03G /dev/VolGroup00/LogVol00


/* resize the volume group while its still mounted */

[root@host]# ext2online /dev/VolGroup00/LogVol00


check the following

[root@host]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
14G 668M 13G 6% /
/dev/sda1 99M 9.1M 85M 10% /boot
none 506M 0 506M 0% /dev/shm

[root@host]# sfdisk -l

Disk /dev/sda: 2088 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

Device Boot Start End #cyls #blocks Id System
/dev/sda1 * 0+ 12 13- 104391 83 Linux
/dev/sda2 13 1043 1031 8281507+ 8e Linux LVM
/dev/sda3 1044 2087 1044 8385930 83 Linux
/dev/sda4 0 - 0 0 0 Empty


now, go on with your life.

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