[OmniOS-discuss] zfs pool 100% busy, disks less than 10%

[Eric Sproul]

On Fri, Oct 31, 2014 at 2:33 AM, Rune Tipsmark <rt at steait.net> wrote:

> Why is this pool showing near 100% busy when the underlying disks are doing
> nothing at all….

Simply put, it's just how the accounting works in iostat.  It treats
the pool like any other device, so if there is even one outstanding
request to the pool, it counts towards the busy%.  Keith W. from
Joyent explained this recently on the illumos-zfs list:
http://www.listbox.com/member/archive/182191/2014/10/sort/time_rev/page/3/entry/18:93/20141017161955:F3E11AB2-563A-11E4-8EDC-D0C677981E2F/

The TL;DR is: if your pool has more than one disk in it, the pool-wide
busy% is useless.

Eric