I have Ubuntu 12.04 with Dropbox installed. Sometimes, when files are downloading (we have a huge shared Dropbox share), I get very high disk activity (HDD led almost continuously bright, with easy to hear HDD movements) for a long time, even though the files being downloaded aren't that huge (max network bandwidth use peaks at 2-3 MB/s, but is 0 most of the time).
iotop, I got the following readings:
282 be/3 root 0.00 B/s 19.06 K/s 0.00 % 94.63 % [jbd2/sda5-8] 767 be/4 simon 3.81 K/s 163.89 K/s 0.00 % 1.79 % dropbox
so it seems that there is something terribly inefficient in the system, but I don't know what.
I already added the "no atime updates" attribute to the Dropbox folder, I'm not sure though whether it works with recently added files. Nevertheless, the results are unchanged.
Actually, I already got the same issue when I had a virtual machine on this partition: I got hangs so bad that the computer was literally unusable for minutes. Now the VM is on another partition with journaling disabled, which seemed to fix the problem... I don't really want to do the same thing to my main file system though.
Currently it's mounted in a quite average way, that is,
/dev/sda5 on / type ext4 (rw,errors=remount-ro)
Did anyone experience similar things? Do you have any ideas what the solution might be?