I've seen lots of comments suggesting that EXT3 is safer & better than reiserfs. I've been using this FS for about 4 years now and never ever had problems.
Before this I used ext2 and then ext3. On ext2 I once lost ALL my files because of a hardware problem, on ext3 a big part of my FS got rearranged and moved to "lost'n'found". On reiser I never ever lost a file, so I don't really understand why people keep suggesting to use ext3 as long as reiser does its job and seems to do it better.
The problems I had were caused by the IDE cable "disconnecting" from time to time from the HDD interface… while the system was running. It was a very specific situation when this happened and it took a really really long time until I changed the cable with a newer one…
I understand that Hans Reiser is in prison now… but why would that matter? We used FAT16/32 for a really really long time now and nobody complained. Nobody even knows if the original developer for that FS is still alive…
Best Answer
Its performance doesn't scale well with multiple processing cores due to the specific implementation.
Prior versions were actually fairly prone to corruption (and I've encountered this multiple times), though that's supposedly resolved in current versions.
Its fsck can actually end up causing more corruption on an already heavily corrupted filesystem.
Upgrading to its successor, Reiser4, requires a complete backup and restore, since it's effectively a completely different filesystem, unlike ext2->ext3->ext4.
There are very few developers actually working on Reiserfs, which means that if and when problems occur, there's not much support to fix them.
Much of this information is from one of the head SuSE developers when they decided to switch their default filesystem from Reiserfs to ext3.