The tune2fs program can add a journal to an existing ext2 file system without altering the data already on the partition. If the file system is already mounted while it is being transitioned, the journal is visible as the file .journal in the root directory of the file system. If the file system is not mounted, the journal is hidden and does not appear in the file system at all.
A default installation of Red Hat Enterprise Linux uses ext3 for all file systems.
To convert an ext2 file system to ext3, log in as root and type,
/sbin/tune2fs -j <file_system>
where <file_system> is an appropriate LVM2 file system.
A valid LVM2 file system could be one of two types of entries:
A mapped device — A logical volume in a volume group, for example, /dev/mapper/VolGroup00-LogVol02.
A static device — A traditional storage volume, for example, /dev/hdbX, where hdb is a storage device name and X is the partition number.
Issue the df command to display mounted file systems.
For the remainder of this section, the sample commands use the following value:
After doing this, be certain to change the partition type from ext2 to ext3 in the /etc/fstab file.
If you are transitioning your root file system, you must use an initrd image (or RAM disk) to boot. To create this, run the mkinitrd program. For information on using the mkinitrd command, type man mkinitrd. Also, make sure your GRUB configuration loads the initrd.
If you fail to make this change, the system still boots, but the file system is mounted as ext2 instead of ext3.