I use a linode as an IMAP mail server, I'm currently storing all my maildirs on an ext3 partition.

I know that a maildirs run better on a reiserfs partitions, will I feel this benifit under UML? Has anyone done this and found an improvment?

So is it really that slow at the moment?

You can get reasonable response times to many files in one directory with ext3 and resier. If it aint broke then dont fix it.

With maildir using one file per email, it tends to eat up inodes really fast. ReiserFS doesn't have as much of a problem with that as ext2/3 does. It does still have it though with a limit on the number of files you can have in one directory. I've hit the limit myself before, but it's much higher than with the default inode ratio the LPM sets (and you could in fact just format a ext2/3 partition for yourself using a custom higher inode ratio that should work fine so you don't run out of inodes). ReiserFS has shown it does work a lot faster in benchmarks with tons of smaller files like your going to get with maildir. I can confirm that rumor, but it's unlikely that you'll notice the difference.

May I suggest one thing though... If you want to move to ReiserFS, format a partition that only holds your mail directories, and keep backups like you should be in the first place. ReiserFS seems to have a lot of disappointed users from broken filesystems (I've heard a lot of comments about fsck.reiser making people's partitions un-recoverable).

I thought I would give all the warnings first, but I am a fan of ReiserFS, and have not run into a single problem in the 3-4 years I've been using it. I've even written a GUI frontend to a reiserfs library for reading ReiserFS partitions under Windows some time ago that I still use to this day. Then again, ext3 has never failed me either, I just like to think towards the future of Reiser4, and the million of possibilities it opens up as a filesystem.

I got burned by ReiserFS. Loss of data is too high a price to pay for increased performance.

I haven't tried ReiserFS 4 so I don't know if it is more reliable than prior versions.

I tried JFS (from IBM) and have been pretty happy with it. Seems very CPU-friendly. But I wouldn't recommend it for your scenario because JFS is relatively slow when it comes to dealing with thousands of files within a single directory (in all other aspects, it is very fast).

You might want to look into XFS if you really MUST improve performance. I haven't tried it yet, but everyone I know who has tried it seems to be quite happy with it and there are fewer unhappy users. It uses substantially more CPU than JFS, but is pretty fast.

If you can, just stick with EXT3. Good luck!

I've used ReiserFS3 on a number of machines now (Slackware 8,9,10,10.1, and Debian Sarge) without a single instance of data loss. I've had servers crash in the middle of heavy IO without corrupting the filesystem.

What happened that caused your data corruption? How could you tell it was Reiser and not your HDD?

I'm just curious. I have no feelings about which FS is "superior" - I've always just used Reiser because I've never had a problem with it.