Book Image

Troubleshooting CentOS

By : Jonathan Hobson
Book Image

Troubleshooting CentOS

By: Jonathan Hobson

Overview of this book

Table of Contents (17 chapters)
Troubleshooting CentOS
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Checking performance with iostat and lsof


Having already discovered how vmstat can be used to provide statistics related to memory management, when troubleshooting performance-related issues an overburdened CPU is yet another area of concern. For this purpose, we can use the iostat command like this:

# iostat

However, to display a more interactive CPU utilization report, you can use the –c option (and provide a numeric value measured in seconds, such as 5 seconds) like this:

# iostat –c 5

Most of the columns should be self-explanatory, but if the system is getting busy, you will see an increase in %iowait, which is used to report on an increase in waiting time for any I/O requests to be completed. Based on this, if the server is transferring or copying a large amount of files, you may also notice additional time being spent at the system level as files will be moved in and out of relevant disk partitions. A feature that is particularly useful when attempting to monitor storage devices in...