iostat was enabled to show latency distributions in Solaris 11.4. However, there is another tool able to show latencies. The fsstat command got this capability as well with the -l option. With this tool you can check latencies from the perspective of the filesystem. It does so for read, write and readdir operations. It’s really simple to use.
root@testbed:~# fsstat -l / 1
read read read write write write rddir rddir rddir
ops bytes time ops bytes time ops bytes time
169K 926M 5n 26K 378M 0n 16.8K 9.95M 38n /
0 0 0n 0 0 0n 0 0 0n /Unlike iostat, which looks at the device-level latencies, the output of fsstat -l displays filesystem-level latencies. This includes, for example, requests that don’t hit the device, as many requests on the filesystem layer are simply answered by the filesystem cache.
I don’t use fsstat as frequently as iostat, nevertheless this was a really useful addition from my perspective.
