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.