[mythtv-users] Performance issues with ext4
bc-mythtv at comcast.net
Sun Dec 27 19:26:45 UTC 2009
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
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
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).
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