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.