Listing Pool-Wide I/O Statistics

With no options, the zpool iostat command displays the accumulated statistics since boot for all pools on the system. For example:

# zpool iostat
               capacity     operations    bandwidth
pool        alloc   free   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
rpool       6.05G  61.9G      0      0    786    107
tank        31.3G  36.7G      4      1   296K  86.1K
----------  -----  -----  -----  -----  -----  -----

Because these statistics are cumulative since boot, bandwidth might appear low if the pool is relatively idle. You can request a more accurate view of current bandwidth usage by specifying an interval. For example:

# zpool iostat tank 2
               capacity     operations    bandwidth
pool        alloc   free   read  write   read  write
----------  -----  -----  -----  -----  -----  -----
tank        18.5G  49.5G      0    187      0  23.3M
tank        18.5G  49.5G      0    464      0  57.7M
tank        18.5G  49.5G      0    457      0  56.6M
tank        18.8G  49.2G      0    435      0  51.3M

In this example, the command displays usage statistics for the pool tank every two seconds until you type Control-C. Alternately, you can specify an additional count argument, which causes the command to terminate after the specified number of iterations. For example, zpool iostat 2 3 would print a summary every two seconds for three iterations, for a total of six seconds. If there is only a single pool, then the statistics are displayed on consecutive lines. If more than one pool exists, then an additional dashed line delineates each iteration to provide visual separation.