2009.09_High-Altitude Euphoria-the Sys Admin's Daily Grind-Lug Camp and Iotop.pdf

The sys admin's daily grind: LUG Camp and Iotop

High-Altitude Euphoria

Immenstadt, Germany, was the site of the 10th anniversary LUG Camp for the founding Linux User Groups

from Germany's Allgäu and Augsburg.

By Charly Kühnast

The 10th LUG Camp saw the Linux faithful trekking into the mountains. Around 120 Linux fans, including

yours truly, met at a school youth hostel in Gschwend near Immenstadt (Figure 1). Nobody had to do without

water: The hostel's own waterfall, fed by meltwater from even higher up, cooled the kegs of beer and even

served as a shower for some hardy souls.

Figure 1: A talk on the topic of WLAN against a typical highland backdrop. LUG Camp 2009 pitched tent at an

altitude of 800 meters at the end of May.

Although LUG Camp traditionally perceives itself more as a geek family gathering with the focus very

obviously on fun, this doesn't mean a complete lack of content: Anybody with the necessary knowledge and

desire could take an LPIC exam, and there were some really excellent talks. Incidentally, the thin mountain air

of Gschwend didn't worry the participants in the least after the chili contest expanded their lungs to at least

twice their normal capacity.

Iotop

Throughput, data this time, is also the domain of the tool that I will look at here. Iotop solves a problem that

has often bugged me: The system is slow because its disks are running all the time, but I can't identify the

process behind it. Iotop [1] gives me exactly this information.

The Python program needs at least kernel 2.6.20 with TASK_DELAY_ACCT and TASK_IO_ACCOUNTING

enabled. When launched, the top line of the output shows the current I/O data rates for read and write access.

Below this is a list of the input/output activity by process (Figure 2).

High-Altitude Euphoria

Figure 2: Iotop lists the disk activity of active processes.

Short Stories

The iotop -o command line makes the output more readable. In this mode, you only see the processes that are

causing I/O right now.

To extend the refresh interval from 1 to 10 seconds, specify -d 10 . Iotop's batch mode is really useful. The

command line

iotop -o -b -d10 -n30 > io.txt

tells Iotop to write the last I/O status 30 times to a file named io.txt at 10-second intervals. This shows how

data rates develop over a period of five minutes.

Conclusions

If your hard disk LEDs are permanently lit, Iotop is indispensable. For me, LUG Camp is equally

indispensable - I've already registered for next year's event.

INFO

[1] Iotop: http://guichaz.free.fr/iotop/

THE AUTHOR

High-Altitude Euphoria

Charly Kühnast is a Unix operating system administrator at the Data Center in Moers, Germany. His tasks

include firewall and DMZ security and availability. He divides his leisure time into hot, wet, and eastern

sectors, where he enjoys cooking, fresh water aquariums, and learning Japanese, respectively.

High-Altitude Euphoria