Hello fellow Linoders! I am just getting started with Linux, so forgive me if this question is a bit noob-ish

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:

http://img691.imageshack.us/img691/4296 ... 114917.jpg

Note the bumps near the end of the 30-day graph:

http://img835.imageshack.us/img835/6140 ... 122118.jpg

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?

run

apt-get install iotop; iotop

It's like top just for disk io.

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.

Check your crons as well, could be something like log rotate, updating the locate database etc etc

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. The 24-hour cycle suggests that it has something to do with cron or log rotation, but even if you don't find the cause, you don't need to be worried.

Crons didn't show anything out of the ordinary from what I could tell, but see below...



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: link. Another couple blips from "syslogd," which is apparently a logging utility daemon: link.

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!