How to resize ext3 or ext4 filesystems

You have a 50G Amazon Elastic Block Storage device, or maybe a 50G Rackspace SSD Cloud Block Storage device that is running low on space. So you clone it and create a 100G drive. But when you mount it on your system, it still only shows 50G. What the #$%&!

This is because the partition and filesystem needs to be expanded to know it has more space!

Assuming that you have the larger drive already attached to your system, first verify the drive size vs the partition size:

[[email protected] ~]# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   20G  0 disk 
└─xvda1 202:1    0   20G  0 part /
xvdb    202:16   0  100G  0 disk 
└─xvdb1 202:17   0   50G  0 part

Checking the output above, you will see that xvdb has 100G available, but the partition, xvdb1, has only 50G. I’ll outline how to expand the filesystem to use all the new space on this ext4 volume.

Unmount the disk if its currently mounted:

[[email protected] ~]# umount /dev/xvdb1

Confirm the drive does not have any filesystem errors:

[[email protected] ~]# e2fsck /dev/xvdb1

Now comes the nail biting part. We need to remove the partition, then recreate it so it will see the entire disk. This guide assumes there is only 1 partition on this drive. This will not remove the data, however never trust notes that you didn’t verify yourself. Make sure you have backups before proceeding!

[[email protected] ~]# fdisk /dev/xvdb
d
n
p
1
enter
enter
t
83
w

Now, once the partition is recreated, you need to run another filesystem check:

[[email protected] ~]# e2fsck -f /dev/xvdb1
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/xvdb1: 13/3276800 files (0.0% non-contiguous), 251700/13107024 blocks

Then resize the filesystem:

[[email protected] ~]# resize2fs /dev/xvdb1
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/xvdb1 to 26214055 (4k) blocks.
The filesystem on /dev/xvdb1 is now 26214055 blocks long.

Finally, mount the volume and confirm it shows the correct space:

[[email protected] ~]# mount -a
[[email protected] ~]# lsblk
NAME    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
xvda    202:0    0   20G  0 disk 
└─xvda1 202:1    0   20G  0 part /
xvdb    202:16   0  100G  0 disk 
└─xvdb1 202:17   0  100G  0 part /mnt

[[email protected] ~]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda1       20G  1.2G   18G   7% /
tmpfs           496M     0  496M   0% /dev/shm
/dev/xvdb1       99G   60M   94G   1% /mnt