8.1 amd64 lockup (maybe zfs or disk related)

[Greg Bonett]

> If the eSATA port is on the motherboard backplane (e.g. a port that's
> soldered to the motherboard), then you're fine.  Be aware that the eSATA
> port may be connected to the JMicron controller, however, which I've
> already said is of questionable quality to begin with.  :-)

I wanted to send a follow up email to let you know it appears the
problem is solved.  I believe the source of the problem was the JMicron
controller as was suggested (and it was connected to my eSATA port).  I
installed a Silicon Image controller and stopped using the eSATA port.
I still need the JMicron controller for my root device (it handles the
IDE disks) but that drive sees very little IO and so far there have been
no lockups. 

Also, now that I'm using the Silicon Image controller I don't get any
"READ_DMA" errors on any disks.  I was able to complete two (for good
measure) zpool scrubs with other sustained high load tasks and all 6 CPU
cores enabled.  No disk errors, no lockups.
 
It appears all is well.  Thanks for the help.

-Greg