Check disk I/O in 2 mins [video]

by hydn 7 years ago

GNU/Linux ◆ xterm ◆ bash 1718 views

If your Linux server is bogged down, your first step is often to use the TOP command in terminal to check load averages and wisely so. However, there are times when TOP shows very high load averages even with low cpu ‘us’ (user) and high cpu ‘id’ (idle) percentages. This is the case in the video above, load averages are above 30 on a server with 24 cores but CPU shows around 70 percent idle. One of the common causes of this condition is disk I/O bottleneck.

Disk I/O are input/output (write/read) operations on a physical disk (or other storage). Requests which involve disk I/O can be slowed greatly if cpu(s) needs to wait on the disk to read or write data. I/O Wait, (more about that above) is the percentage of time the CPU has to wait on disk. To begin, lets looks at how we can confirm if disk I/O is slowing down application performance by using a few terminal command line tools (top, atop and iotop) on a LEMP installed dedicated server.

Continued… http://bit.ly/iowait

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Using top: checking kswap, io wa (wait) 00:33

by hydn 6 years ago

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