Ubuntu – Good filesystem for /tmp

I have found the following the answer https://www.redhat.com/archives/ext3-users/2009-January/msg00026.html, from Theodore Tso, an ext4 developer.

If you set the reserved block count to zero, it won't affect performance much except if you run for long periods of time (with lots of file creates and deletes) while the filesystem is almost full (i.e., say above 95%), at which point you'll be subject to fragmentation problems. Ext4's multi-block allocator is much more fragmentation resistant, because it tries much harder to find contiguous blocks, so even if you don't enable the other ext4 features, you'll see better results simply mounting an ext3 filesystem using ext4 before the filesystem gets completely full.

If you are just using the filesystem for long-term archive, where files aren't changing very often (i.e., a huge mp3 or video store), it obviously won't matter.

Wikipedia covers most of this:

• http://en.wikipedia.org/wiki/Ext3
• http://en.wikipedia.org/wiki/Ext4

The big advantage of ext3 is journalling, which means you don't need to fsck every time you unmount uncleanly (e.g. power failure / kernel panic). ext4 makes fscking much faster, when you do need to.

It's hard to know whether ext3 or ext4 will be faster than ext2 for your use case. I know for some workloads they will be slower.

The freezing problem sounds like either thrashing or a dying hard drive.

Chance of data loss is minimal, assuming the person doing the upgrade doesn't do something stupid.