How to resize a logical volume and a reiserfs or ext3 filesystem :


Gather information

Type df -h to list the filesystem we would like to increase.

Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LVROOT 4.0G  3.4G  480M  90% /

We would like to increase the root filesystem by 500M so we need to determine if the volume group (VolGroup00) listed above has enough free space.

To do this type vgdisplay

  --- Volume group ---
  VG Name               VolGroup00
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  7
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                5
  Open LV               5
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               136.42 GB
  PE Size               4.00 MB
  Total PE              34924
  Alloc PE / Size       5760 / 22.50 GB
  Free  PE / Size       29164 / 113.92 GB
  VG UUID               efvr7g-grgf5g-V0SP-45gdf-Xber-VKzj-fg5hf

The "Free PE / Size 29164 / 113.92 GB" line shows that we have 113.92 GB free in this volume group.

Type lvdisplay to show additional information about the logical volumes on the server.

  --- Logical volume ---
  LV Name                /dev/VolGroup00/LVROOT
  VG Name                VolGroup00
  LV UUID                fdsff5-Ma8z-8rr3-5ytgb-fht7-N37h-465yhh
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                4.00 GB
  Current LE             1152
  Segments               2
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:0


Increase logical volume size

In this case we have identified /dev/VolGroup00/LVROOT as being the logical volume to be modified

The current size of the /dev/VolGroup00/LVROOT logical volume is 4G and we need to increase the size to 4.5G

The first step is to increase the logical volume and the second step to increase the filesystem

To increase the logical volume size use the lvextend command as follows

lvextend -L 4.5G /dev/VolGroup00/LVROOT


Increase the filesystem size

Then to increase the size of the filesystem to equal the new size of the LV, do one of the following depending on whether you have an reiserfs or ext3 filesystem.

To check what filesystems you are using type mount

/dev/mapper/VolGroup00-LVROOT on / type ext3 (rw)

We can see in this case we are using the ext3 filesystem
Reiserfs

resize_reiserfs /dev/VolGroup00/LVROOT
ext3

ext2online -d -v /dev/VolGroup00/LVROOT

or

resize2fs -p /dev/VolGroup00/LVROOT



Type df -k and lvdisplay to check that all is as expected


Decrease the filesystem size
ext3

We would like to decrease the size of the /home filesystem by 2GB.

First check the current size.

[root@linux1 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_linux1-lv_root
                       50G  4.8G   42G  11% /
tmpfs                1002M   88K 1002M   1% /dev/shm
/dev/sda1             485M   29M  431M   7% /boot
/dev/mapper/vg_linux1-lv_home
                       20G  217M   19G   2% /home

Then resize the filesystem before resizing the LV to prevent data loss, however it is still important to backup the fileystem first.

Then try to reduce the size of the /home filesystem as follows.

[root@linux1 /]# resize2fs -p /dev/vg_linux1/lv_home 18G
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_linux1/lv_home is mounted on /home; on-line resizing required
On-line shrinking from 5267456 to 4718592 not supported.

This shows that the filesystem needs to be unmounted first.

[root@linux1 /]# umount /home

Ok lets try again.

[root@linux1 /]# resize2fs -p /dev/vg_linux1/lv_home 18G
resize2fs 1.41.12 (17-May-2010)
Please run 'e2fsck -f /dev/vg_linux1/lv_home' first.

We are still unable to shrink the filesystem until we run the filesystem checker e2fsck

[root@linux1 /]# e2fsck -f /dev/vg_linux1/lv_home
e2fsck 1.41.12 (17-May-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/vg_linux1/lv_home: 212/1318912 files (2.8% non-contiguous), 138179/5267456 blocks

Ok lets have another go.

[root@linux1 /]# resize2fs -p /dev/vg_linux1/lv_home 18G
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/vg_linux1/lv_home to 4718592 (4k) blocks.
Begin pass 3 (max = 161)
Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
The filesystem on /dev/vg_linux1/lv_home is now 4718592 blocks long.

Success!

Lets take a look.

[root@linux1 /]# mount /home
[root@linux1 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_linux1-lv_root
                       50G  4.8G   42G  11% /
tmpfs                1002M   88K 1002M   1% /dev/shm
/dev/sda1             485M   29M  431M   7% /boot
/dev/mapper/vg_linux1-lv_home
                       18G  217M   17G   2% /home

reiserfs

The following procedure will shrink the reiserfs filesystem mounted on /logs from 20G to 10G

[root@linux1 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/system-logs
                       20G  33M   20G  1% /logs

[root@linux1 /]# mount
/dev/mapper/system-logs on /logs type reiserfs (rw,acl,user_xattr)
[root@linux1 /]# umount /logs
[root@linux1 /]# resize_reiserfs -s -10G /dev/system/logs
[root@linux1 /]# mount /dev/system/logs /logs


Decrease the LV size

Ok we just need to reduce the size of the LV now.

[root@linux1 /]# lvreduce -L 18G /dev/vg_linux1/lv_home
  WARNING: Reducing active logical volume to 18.00 GiB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lv_home? [y/n]: y
  Reducing logical volume lv_home to 18.00 GiB
  Logical volume lv_home successfully resized