Comments on Watching Hard Drive Activity With iotop On Ubuntu 8.10 And Debian Lenny
Watching Hard Drive Activity With iotop On Ubuntu 8.10 And Debian Lenny This article shows how you can watch your hard drive activity with iotop on Ubuntu 8.10 and Debian Lenny. iotop watches I/O usage information output by the Linux kernel and displays a table of current I/O usage by processes or threads on the system. iotop displays columns for the I/O bandwidth read and written by each process/thread during the sampling period. It also displays the percentage of time the thread/process spent while swapping in and while waiting on I/O. In addition the total I/O bandwidth read and written during the sampling period is displayed at the top of the interface.
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Comments
Definitely that’s a step in the right direction.
Unfortunately it’s still hard to tell who’s wasting most disk IO in too many situations.
Suppose you have two processes - dd and mysqld.
dd is doing massive linear IO and its throughput is 10MB/s. Let’s say dd reads from a slow USB drive and it’s limited to 10MB/s because of the slow reads from the USB.
At the same time MySQL is doing a lot of very small but random IO. A modern SATA 7200 rpm disk drive is only capable of about 90 IO operations per second (IOPS).
So ultimately most of the disk time would be occupied by the mysqld. Still iotop would show dd as the bigger IO user.
Btw, there's also atop which is a good multi-purpose top like tool. It shows CPU, IO, Network load and more. There's also the atop kernel patch that adds some extra performance counters.
– Teodor Milkov
nice, been looking for a long time for something like that. Now if there only was a nice colorful ncurses based version of it, you know like top --> htop ;)
Thx for that article.
I use apt-get because I log in as root on Debian. On Ubuntu, I don't enable the root account because this is frowned upon by the Ubuntu community. Therefore I use sudo.
Why did you use sudo apt-get with Ubuntu and only apt-get with Lenny? Got something against Lenny? The way my Lenny's set up I need root permission to use apt-get, for security reasons.
When tuning notebook for better battery life I have found "pidstat" tool irreplaceable.
"pidstat -d 10" would show every 10 seconds list of processes which did I/O.
Very handy.
IIRC it is part of sysstat package.