8.0-RELEASE: disk IO temporarily hangs up (ZFS or ATA relatedproblem)

[Alexander Zagrebin]

Big thanks for your reply! 

> We see a very similar pattern on straight ufs disks on an 
> areca controller. Machine
> console becomes totally unresponsive 30 or so seconds at a 
> time, so it maybe
> something more intergral to device operation, buffercache or 
> something?

In my case console is responsive, but there are delays when
starting command due to disk busy.

> The IO load on the machine is being generated by updating 
> rrds files in mrtg
> for a few hundred switch ports and a few thousand servers.

I'm noticing delays (lockups) even if system is idle.

-- 
Alexander Zagrebin