When an ext3 file system reports being "read-only" quick action needs to be taken.

• Power off the server ('init 0') to avoid data loss.
• Boot into a rescue environment
• Do not allow the rescue to mount the drives. For Red Hat, choose the 'Skip' option when prompted to find your RHEL installation.
• Once in the rescue shell, locate the / file system (ex: /dev/sda5)
• Remove the existing journal:

 sh#   tune2fs -O ^has_journal /dev/hda5

If this fails because of the needs_recovery flag preform the following

 sh# debugfs -w /dev/sda5
 debugfs: features ^needs_recovery
 debugfs: quit

• Now, perform a fsck operation. Note, use the -y option with caution. You might want to just see how bad the corruption is first before you say "YES" to anything.

 sh#  fsck.ext2 -f /dev/sda5

• Now, if your fsck looks good, rebuild the journal

 sh#  tune2fs -j /dev/sda5

• Mount the filesystem and make sure its clean

 sh#  mkdir /mnt/fixed && mount -t ext3 /dev/sda5 /mnt/fixed

• If done, then unmount the file system, and bring it back up.

 sh#  cd / ; umount /mnt/fixed  && reboot && exit

NB: Stolen from an old how-to at work in case the Wiki it's on goes way abruptly; I didn't write this -- Robot Terror