[mythtv-users] Performance issues with ext4

[Boleslaw Ciesielski]

I have not seen it mentioned before, so I just want to relay my experience.

About three weeks ago I upgraded my main myth box from Fedora 10 to 
Fedora 12. It was actually a clean install, though I copied several 
config files and did a full database restore. I was already running 0.22 
then.

Before the upgrade I was using ext3 for everything. Fedora 12 by default 
uses ext4 for the root and boot partitions. I was aware of this but did 
not change from the default because I decided to give ext4 a try. So, my 
root partition (which included mysql database) ended up ext4 and video 
partition stayed ext3 (it was not reformatted).

After the upgrade everything was working fine, but I noticed various 
performance issues like random I/O hangs etc. The only repeatable 
problem was that mythfilldatabase was taking about 20min to run. In 
particular, the "Marking episode first/last showings" phases at the end 
took about 8min each (whereas they took about 15sec each before the 
upgrade).

I didn't know right away if ext4 was to blame. Perhaps ext4 needed some 
tuning that I wasn't aware of. But I did not have to do anything for 
ext3. So, as an experiment, I booted the rescue CD, backed up the root 
partition (with tar), reformatted to ext3 and restored everything. Boom, 
performance is back. mythfilldatabase takes 3min total to run. So now I 
have little incentive to figure out what was wrong, since it would 
require another downtime and reformat...

I guess I am sticking with ext3 at least until Fedora 14 (I only use the 
even numbered ones).

Bolek