Strange Disc I/O
I have a pretty much default install of Debian 5.0 on my Linode 512. I've got Apache installed so far, but it's fire-walled safely away, and the logs confirm this. I've also got logwatch installed, and the logs it sends confirms I have no malicious activity.
Yet, the Linode disc I/O graph shows continuous activity:
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Note the bumps near the end of the 30-day graph:
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Now, granted, I have no idea what the "I/O rate" units are, so maybe that's next to no activity.
But I see the same trend repeating every day; runs at a low level all day with a few hours of no activity.
Maybe I don't care, seeing as it's probably running on some high-performance disc array or what-not.
But I'm curious as to why, with essentially no software installed, Debian is continuously hitting the disc.
Any ideas? How can I debug this?~~~~
5 Replies
@obs:
run iotop
Cool! However my linode just quit doing disc use again; sorting by reads or writes all show 0 B/s.
I'll have to wait until it starts up again.
It seems like it may be doing this activity only on idle.
@obs:
Check your crons as well, could be something like log rotate, updating the locate database etc etc
Crons didn't show anything out of the ordinary from what I could tell, but see below…
@hybinet:
By the way, single-digit I/O numbers are next to nothing. Those bumps would have been invisible if your site had a moderate level of traffic.
Sounds good! Even when the graph shows activity (aka, right now), there's nothing going on in iotop. Occasionally I get a blip from "kjournald," which appears to be the EXT3 journaling daemon: linklink
I guess this probably goes on all the time, and I'm just noticing it because I have fine-grain tools to see it. I'm betting this sort of stuff goes on all the time on my Windows box and I just don't notice
Thanks for your help!