Solaris I/O Latency

Starting with Solaris 11.4 you got a new interface for device latency without using dtrace. The information was always there but now you can use a “human readable” command. That might bring easier understanding and analyzing the disk subsystem.

I ran an IO calibrate in a 18c database which resides on NVMe flash drives:

root@t7primary01:~# iostat -x -L c5t1d0 c1t1d0 1
                     extended device statistics
device     r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b
blkdev2   29.9   13.1  185.7   81.4  0.0  0.0    0.0    0.1   0   0
latency          range         count      density distribution
                  <4us             0        0.00%        0.00%
                 4-8us          3527        0.02%        0.02%
                8-16us       1224166        5.74%        5.76%
               16-32us       4020858       18.85%       24.61%
               32-64us       1225365        5.75%       30.35%
              64-128us      13243355       62.10%       92.45%
             128-256us       1561222        7.32%       99.77%
             256-512us         34758        0.16%       99.93%
            512-1024us          4642        0.02%       99.96%
                 1-2ms          3624        0.02%       99.97%
                 2-4ms          5758        0.03%      100.00%
                 4-8ms            97        0.00%      100.00%
                8-16ms            33        0.00%      100.00%
                 >16ms             0        0.00%      100.00%
                 total      21327405
blkdev3   32.0   14.0  198.5   86.8  0.0  0.0    0.0    0.1   0   0
latency          range         count      density distribution
                  <4us             0        0.00%        0.00%
                 4-8us          2848        0.01%        0.01%
                8-16us       1280834        5.62%        5.64%
               16-32us       4197957       18.44%       24.07%
               32-64us       1355014        5.95%       30.02%
              64-128us      14167408       62.22%       92.24%
             128-256us       1734203        7.62%       99.86%
             256-512us         29629        0.13%       99.99%
            512-1024us           895        0.00%       99.99%
                 1-2ms           614        0.00%      100.00%
                 2-4ms           939        0.00%      100.00%
                 4-8ms           104        0.00%      100.00%
                8-16ms            27        0.00%      100.00%
                 >16ms             0        0.00%      100.00%
                     extended device statistics
device     r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b
blkdev2 49234.1    1.0 307781.4   20.0  0.0  5.4    0.0    0.1   0  20
latency          range         count      density distribution
                 <16us             0        0.00%        0.00%
               16-32us             1        0.00%        0.00%
               32-64us            21        0.04%        0.05%
              64-128us         42324       88.06%       88.10%
             128-256us          5647       11.75%       99.85%
             256-512us            67        0.14%       99.99%
            512-1024us             1        0.00%       99.99%
                 1-2ms             1        0.00%      100.00%
                 2-4ms             2        0.00%      100.00%
                  >4ms             0        0.00%      100.00%
                 total         48064
blkdev3 52145.2    0.0 325741.9    0.0  0.0  5.7    0.0    0.1   0  18
latency          range         count      density distribution
                 <32us             0        0.00%        0.00%
               32-64us            28        0.05%        0.05%
              64-128us         44430       87.26%       87.31%
             128-256us          6374       12.52%       99.83%
             256-512us            84        0.16%       99.99%
            512-1024us             3        0.01%      100.00%
               >1024us             0        0.00%      100.00%
                 total         50919

That’s a nice overview…

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