Shrink EXT3 partition Without Losing Data

Shrink EXT3 partition Without Losing Data

Release:


RedHat Enterprise Linux


Problem:


Resize the ext3 partition without losing data


Solution:


This article shows how to shrink the ext3 partition without losing data. This can be quite useful if you do not use LVM


Note: The partition that is to be resized must be unmounted when we do the resizing


Shrinking an ext3 Partition:


1) Check the disk usage of the server before proceeding


          # df –h


          Filesystem   Size       Used     Avail      Use%       Mounted on
          /dev/sda3    4.4G       2.4G     1.8G       58%          /
          /dev/sda1    99M        14M      80M        15%          /boot
          tmpfs       125M       0        125M        0%          /dev/shm


2) Boot the server into linux rescue mode


Note: If the partition you want to resize doesn't hold any system files, you can do everything from the original system; the steps are the same, just omit booting into rescue system


3) Run the filesystem-specific fsck on the filesystem.


               # fsck –n /dev/sda3


         e2fsck 1.39 (29-May-2006)
         /dev/sda3: clean, 115974/577152 files, 636274/1152640 blocks


4) Remove the journal from /dev/sda3, thus turning it into an ext2 partition


         # tune2fs -O ^has_journal /dev/sda3


         tune2fs 1.39 (29-May-2006)


5) Run fsck on the filesystem


         # e2fsck –f /dev/sda3


         e2fsck 1.39 (29-May-2006)
         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/sda3: clean, 115974/577152 files (0.5% non-contiguous), 636274/1152640 blocks


6) Now resize the filesystem using resize2fs. resize2fs can resize ext2 file systems, but not ext3 file systems


         # resize2fs /dev/sda1 3600M


         resize2fs 1.39 (29-May-2006)
         Resizing the filesystem on /dev/sda3 to 921600 (4k) blocks.
         The filesystem on /dev/sda3 is now 921600 blocks long.


Please take note of the amount of blocks (921600) and their size (4k).


Note: Currently, 2.3 GB are used on /dev/sda3 (see the df -h output above), so it's safe to shrink it from 4.4GB to about 3.6GB (if you make it smaller than 2.3GB, you will lose data!).


7) Now we delete our /dev/sda1 partition (don't be afraid, no data will be lost) and create a new, smaller one (but still big enough to hold our resized file system!).


        # fdisk /dev/sda


        Command (m for help): d
        Partition number (1-4): 3
        Command (m for help): n
        Command action
        l logical (5 or over)
        p primary partition (1-4)
        p
        Partition number (1-4): 3
        First cylinder (79-652, default 79):
        Using default value 79
        Last cylinder or +size or +sizeM or +sizeK (79-652, default 652): +3870720K


        Command (m for help): w
        The partition table has been altered!
        Calling ioctl() to re-read partition table.
        Syncing disks.


Note: We multiply the amount of blocks from the resize2fs output (921600) by the size of a block (4k), and to go sure the partition is big enough, we add 3 to 5% to it (5% was enough for me, but if you want to go sure take 3%)


                   921600 * 4k * 1.05 = 3870720k


8) Now restart the server once and boot into the rescue mode once again


        # exit


9) Once again run the filesystem-specific fsck on the filesystem


        # fsck –n /dev/sda3


        fsck 1.39 (29-May-2006)
        e2fsck 1.39 (29-May-2006)
        /dev/sda3: clean, 115962/464928 files, 599592/921600 blocks


10) Now create the journal on our new /dev/sda3, thus turning it into an ext3 partition again


        # tune2fs -j /dev/sda3


        tune2fs 1.39 (29-May-2006)
        Creating journal inode: done
        This filesystem will be automatically checked every 25 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.


11) Now restart the server and boot from the harddisk.


        # exit