[OpenIndiana-discuss] Sudden ZFS performance issue

[Saso Kiselkov]

On 05/07/2013 21:00, wim at vandenberge.us wrote:
> Latencytop reports the following continuously for the pool process and it
> doesn’t change significantly under load, which looks ok to me:
> 
> genunix`cv_wait genunix`taskq_threa        14491    9.6 msec    6.2  sec  99.3 %
> 
> Wait for available CPU                     14618   44.9 usec    9.8 msec   0.5 %
> 
> Adapt. lock spin                           14501   24.2 usec    1.7 msec   0.3 %
> 
> genunix`turnstile_block unix`mutex_           48  174.5 usec  453.9 usec   0.0 %
> 
> Spinlock spin                                194   35.4 usec  309.0 usec   0.0 %
> 
> genunix`turnstile_block unix`mutex_           20  315.5 usec    3.1 msec   0.0 %
> 
> genunix`turnstile_block unix`mutex_           62   56.1 usec  124.5 usec   0.0 %
> 
>  I realize 64GB is low for this size of storage. would it be conceivable that I
> reached some threshold there?

What's 'iostat -xn' showing in the asvc_t and %b columns? Isn't some
disk taking an excessive amount of time to fulfill I/O requests? For
example one of the disks in the pool showing 100% busy and very large
service times can slow down the whole raidz and by extension the pool
(all blocks read from the raidz will incur a significant hit).

Cheers,
-- 
Saso