Comment 79 for bug 607560

I tried using an fstab option to make ext4 sync its journal data less often, but found that Ubuntu's power management scripts were overriding my change. After a bit of reading and poking around, I created /etc/pm/config.d/10_journal_commit_time containing this line:

JOURNAL_COMMIT_TIME_AC=30

This sets the journal sync interval to 30 seconds when on AC power, which I feel is safe on my system because I'm using a UPS.

After I made this change, stopped my kernel from updating atime on every file access, and rebooted, disk activity settled down to a tolerable rate. It's now more like what I expected based on the applications I use.