Request assistance: "Excessive I/O Usage"

I was just sent a message that my Linode has excessive I/O usage, and told that this has been the case for quite some time. I am being asked to tone this down. I don't know how to find out what's causing it and fix it.

It was suggested that I run "iostat," so if someone might be able to walk me through doing that, and what the results of it might be telling me, that would be very helpful also.

Thank you very much for any assistance.

7 Replies

What issues are you encountering? If you google for "how to iostat linux" you end up on one of these links:

http://www.cyberciti.biz/tips/linux-dis … howto.html">http://www.cyberciti.biz/tips/linux-disk-performance-monitoring-howto.html

http://www.pythian.com/blog/basic-io-mo … -on-linux/">http://www.pythian.com/blog/basic-io-monitoring-on-linux/

Are you having difficulties running iostat? All it does is tell you which processes are using i/o - and how much. So if there are processes there running at very high I/O while this is not expected you'll have to look into fixing that.

@Nuvini:

What issues are you encountering?
I am personally not experiencing any issues. This is all coming from Linode sending me a message saying, "you have excessive I/O usage; please fix it."

RE: iostat, I found this information at the 2nd link you provided, and have a couple of questions.

> iostat -x [-d]

specifying 5 makes iostat dump 5 seconds of average IO characteristics, every 5 seconds until it’s stopped.

I do this in my Lish Ajax Console?

In that window, at the prompt, I just type that exact command above, but filling in an interval?

What is a good interval value to use that will be helpful?

How long should I leave it running?

After that, how do I stop it? This seems pretty important to me. I don't want to start the iostat thing running and then not be able to stop it.

Thank you very much for further details so I can start to try and find out where the problem is and fix it.

@jebblue:

You could try nethogs.

Jebblue, thank you, this sounds like it could be a good suggestion. But I need some more help to be able to try it. Here's the information I found based on your post, and what I understand and don't understand how to do.

I found this page: http://www.cyberciti.biz/faq/linux-find … bandwidth/">http://www.cyberciti.biz/faq/linux-find-out-what-process-is-using-bandwidth/

which seems to be a walkthrough for installing nethogs, but it brings me to other questions.

I am looking at the section for CentOS4.

It says, > First turn on EPEL repo and type the following yum command to install nethogs package:

yum install nethogs

I looked at their link to EPEL at http://www.cyberciti.biz/faq/fedora-sl- … epel-repo/">http://www.cyberciti.biz/faq/fedora-sl-centos-redhat6-enable-epel-repo/

This seems to walk through installing EPEL, but I don't really understand the "enabled repos" and "packages." So after installing it, what is it I would need to do before typing the install nethogs command?

I'm sorry for my very low level of knowledge making me ask so many questions and really appreciate any help so I can solve this problem!

Once nethogs is installed:

sudo nethogs

Ok, now I'm also being told by the Linode admins that I can't install iostat because I'm on CentOS 4.

I'm being told two things. One is to upgrade to CentOS 7, which I will do if I can find someone who knows how to do it properly and how it will affect my server.

But meanwhile, it was suggested I look at "iotop" to find the culprit of the excessive I/O issue. I don't know what that is, so have to start from the beginning asking where to find that/how to use it, etc.

Any info on iotop? Thank you!

You're gonna want to get a sysadmin. If you know nothing of Linux you won't be able to interpret the iostat results.

You can do it via lish - or just via SSH. To close the program once you're done, use CTRL + C.

I think it'd be better to use iotop. That live updates the I/O % used. You don't need parameters to run that either. There's a little guide here: http://www.tecmint.com/install-iotop-mo … nd-fedora/">http://www.tecmint.com/install-iotop-monitor-linux-disk-io-in-rhel-centos-and-fedora/

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