Ext4

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Contents

Introduction

Wikipedia: "the ext4 or fourth extended filesystem is a journaling file system for Linux, developed as the successor to Ext3." Its features include bigger filesystem/file sizes, multiblock allocation, fast fsck, online defragmentation and others. It is supported by kernels 2.6.29 and later.

Installation

New installation

During the installation of MEPIS 11, there is a pull-down menu for the file system to be used. Select ext4.

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Existing ext3 installation

Before converting existing ext3 partitions to ext4, be sure to fully back up the partitions using cloning or partition imaging software. Be sure to follow the instructions below CAREFULLY. This example assumes sda5 = / and sda6 = /home. Modify the instructions according to your partition numbering. If / and /home are on the same ext3 partition, you will only need to convert that one partition.

1. Boot the MEPIS Live CD/DVD (SM 8.5 or later will work).

2. With sda5 and sda6 UNMOUNTED, open a Konsole and apply the following code as root:

tune2fs -O extents,uninit_bg,dir_index /dev/sda5 
fsck -pf /dev/sda5 
tune2fs -O extents,uninit_bg,dir_index /dev/sda6 
fsck -pf /dev/sda6 
mount -t ext4 /dev/sda5 /mnt/sda5

Notes:

The '-O', above, is 'hyphen followed by capital letter O'.
The fsck steps are necessary and they might take a long time to complete. Do NOT interrupt the process before it is finished.
The last command mounts / so that certain files can be modified, as explained in Steps 3 and 4.
3. Open /mnt/sda5/boot/grub/menu.lst with KWrite, append
rootfstype=ext4
to the boot code(s), and save.

4. Open /mnt/sda5/etc/fstab with KWrite and change 'ext3' to 'ext4' in the entries for / and /home above the #Dynamic line, and save.

5. Use the MEPIS System Assistant to Repair System Boot, installing GRUB in the proper location (MBR or /). Do NOT select 'Update boot menu' but DO select 'Use initrd (recommended)'.

6. Verify that / and /home are converted to ext4 by opening the KDE Partition Manager and viewing their properties.

You should now be able to exit the Live CD and boot MEPIS from the newly-converted ext4 partitions.

If you convert non-system partitions from ext3 to ext4, you do NOT have to perform Steps 3-5; however, if there are any entries for these partitions above the #Dynamic line in /etc/fstab, you DO need to change 'ext3' to 'ext4' in fstab so they are properly mounted at boot time.


Note: Any back-up partition images made before conversions to ext4 will restore the partitions as ext3. After conversions, you will have to create new partition images in order to restore partitions as ext4 from the back-ups. Make sure your imaging software supports ext4.

Use

For details on how to use the new features of the ext4 filesystem, consult the "ext4 Howto" listed under Links.

Tips and tricks

Links

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