Switching from EXT3 to EXT4

I will be upgrading all my drivers to the new EXT4 format in OpenSUSE 11.2 and I was curious if my drives will have to be reformatted to use the EXT4 format or will I be able to get away with my data intact after converting formats?

The conversion from ext3 to ext4 can be done in-situ. If you do a search on say the terms: ext3 ext4 conversion, you will find any of a number of tutorials on how to do this.


Migrating existing ext3 drives to ext4 should be possible without data loss. However, having a backup is strongly recommended. I did not try the conversion myself, but there was some discussion of this issue recently on this forum. You may try the search function.

There is one problem with upgrading ext3 to ext4. New features of ext4 (extents, about the rest i am not sure) won’t work on old data. Only new data will use the new features. Best is to use some live CD to copy the data somewhere, format the partitions to ext4 and copy the data back to those new ext4 partitions. That way you will start with 0% fragmentation and you will use all those new features on ALL data.

Yes, it’s correct that extents will not be used on existing files, but the other features will work. Depends on how keen you are to get the last bit of performance improvement by using extents. A freshly created ext4 filesystem and a data restore is best, but if that is not feasible for one reason or another, you can do the conversion in-situ. As always with anything involving large changes to data handling, backup, backup, backup.

There is an e4defrag program, but I could only find a work-in-progress version when I went looking and it wouldn’t work anyway when compiled. This on a test machine that I don’t care about.

Thanks for the feed back guys, I appreciate it.

I have looked into the topic more and concluded that its not worth the risk of any data loss converting my old ext3 filesystem to the ext4 filesystem.

I wanted to take the shortcut without any risk involved, but with business critical data, I just can’t take the risk and will just have to do things the longer way.

I can put up with a day or two of downtime to get the most out of my hardware with the ext4 filesystem.