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This week we've added articles on Linux timekeeping with NTP and a couple monitoring tools that can help track down I/O and swap use.

NTP is the "Network Time Protocol", and it can be used to set your server's clock. Slices running newer kernels will benefit from this since the switch to pvops kernels means that those slices no longer get their time from the hardware clock.

Using NTP to sync time

The first monitoring tool we look at is "iotop". You use iotop in the same way you'd use top, but instead of checking CPU and memory use you're looking at swap activity and disk input/ouput (I/O). You run iotop, you watch the numbers change, and you see which processes are using more swap or causing more disk activity. Easy.

Using iotop to check I/O and swap

The other monitoring tool we examine is "dstat". Like iotop dstat can be used to look at swap use and disk I/O, reporting the process using the most of each, but it can also report a lot of other system stuff. And it does it in the order you choose, with pretty colors to boot. Think of it as a really beefy vmstat.

Using dstat to check I/O and swap

Using dstat with scripts and external modules

For CentOS and Red Hat users we recommend using dstat because of the version of python currently installed with those distributions. It's possible to run iotop on those distributions, but only if you install a separate (newer) python instance just for iotop.

If you have any questions or concerns regarding these or other topics, visit us in SliceChat or contact us via email at support@slicehost.com. Our team is available 24 hours a day, 7 days a week.