I am monitoring the IO and SWAP usage of a process in my backup server. I executed dstat -rs 5
and this was an example output:
--io/total- ----swap---
read writ| used free
92.0 57.3 |3228k 514M
289 104 |3468k 514M
270 202 |3472k 514M
363 184 |3612k 514M
237 124 |3740k 514M
377 302 |4168k 514M
113 24.6 |4916k 513M
153 118 |4992k 513M
263 32.6 |6088k 512M
295 242 |6332k 511M
The values from swap
columns are pretty straightforward. But what do the values from io/total
mean? Which unit is being used and what are the range of this measurement?
Best Answer
From the manpage:
These are read and write requests issued to all block devices in the system:
Requests are just a count, so they they don't have units like MB/s, sectors/s etc. For those numbers try
iostat
.As far as a range, it depends entirely on the device(s) in question and the type of requests. Generally I find requests good indicators of traffic but little else. As an alternative,
dstat
with the-c
flag lets you see wait% of CPU, which is how long the CPU is waiting for IO requests to return and is a more tangible metric as far as impact on your system / workload.