With the 10.2 release, openSUSE announced a switch from reiserFS to ext3 as their default filesystem format. The reason given was that development work on reiserFS-3 has come to a halt and SuSE was the only Linux distribution championing it. This gave me a twinge of regret as I had dwelled on this decision when formatting my /home filesystem during SuSE 10.0 installation and eventually chose reiserFS.

Even though openSUSE 10.2 will support reiserFS partitions, the handwriting is on the wall. I decided to convert my /home filesystem before upgrading from SuSE 10 to openSUSE 10.2. After rereading a comparison review of the various Linux filesystem formats, I chose ext3.

I have been using star to do backups and was planning to use it to backup to a file, then restore onto a newly created ext3 partition. Then I discovered the Synchronizing Filesystems section in the star man page which describes a direct filesystem to filesystem transfer. No intermediate backup file is required, cutting both the time and chances of error in half.

Conversion Plan:

• Create an ext3 clone of my existing reiserFS /home partition on an unused 30GB partition using star.
• Use this new /home with my current SUSE 10 configuration to be sure the transfer is correct before erasing the data from the reiserFS /home partition. In particular, I want to verify that the symbolic and hard links have been transferred correctly.
• Reformat the old reiserFS 80GB partition to ext3, then run star a second time to move the /home filesystem back onto the 80GB partition.

This procedure requires a spare disk or disk partition, whereas doing a backup & restore to a file only requires enough free space on an existing partition to hold the backup file. But on the plus side, I never destroy my correctly functioning partition until I’ve fully tested the new one. If something goes wrong, I just fall back to previous step and try again.

Command Sequence:

1. umount /export/sda9 # unused partition (currently formatted as reiserFS)
2. mkfs.ext3 -nv /dev/sda9 # look before leaping
   
3. mkfs.ext3 -v /dev/sda9 # reformat as ext3
4. Edit /etc/fstab to change sda9 mount from reiserfs to ext3:
   /dev/sda9 /export/sda9 ext3 defaults 1 2
   
5. mount /export/sda9
6. star -c -xdev -sparse -acl -link-dirs level=0 -C /export/sda8 . |
star -xpU -restore -C /export/sda9 # filesystem sync
   
7. diff -r /export/sda{8,9}/home # verification (takes a while)
   
8. Edit /etc/fstab to convert “bind” mount from sda8/reiserFS to sda9/ext3:
   /export/sda9/home /home ext3 bind 0 0
9. reboot

I ran the new sda9 /home partition for a few weeks to see if any latent problems surfaced. Satisfied that the procedure was sound, I performed the same sequence from sda9 to sda8, ending up with /home back on its original 80GB partition as an ext3 filesystem.