On 30 August 2014 17:07, Brian May <brian@microcomaustralia.com.au> wrote:
Another thought: really need to make sure cron isn't doing anything at the time. It doesn't show up on top, but need to double check this. Hmm. Looks like I do have anacron installed, so cron jobs do run when I turn the computer on. According to my log files, all cron jobs should have terminated when I saw the high iowait time this morning, and didn't run for long in any case. Unless something is forking and continues to run after cron reports it finished.
I was running a unison sync to a remote ssh server, iotop was saying no (or low) disk I/O, top says up to 60% iowait, and basic tasks (e.g. clicking on xterm or selecting text in xterm) take ages (system appears to be frozen). Oh, and no swap being used, have 16GB ram with relatively few processes running. This seems to be typical. iotop and iosnoop don't seem to report anything abnormal that I can see using the disk. There are cron jobs that run at times, however these problems occur with no cron jobs running (and basic cron jobs shouldn't kill a modern system in any case). Not absolutely convinced this is a disk I/O problem, however something weird is happening here. -- Brian May <brian@microcomaustralia.com.au>