FBSD 10.3 + ZFS + Sun x4500 = utter lock up.

[Lee Damon]

FreeBSD [redacted] 10.3-STABLE FreeBSD 10.3-STABLE #2 r313008: Tue Jan
31 01:50:49 PST 2017     lvd@[redacted]:/usr/obj/usr/src/sys/GENERIC  amd64

I'm trying to get FBSD 10.3 working on a Sun x4500 (don't ask) for use
as a ZFS-based backup server. However, whenever any amount of data is
put into a zpool and then zpool scrub is run the host locks up hard. On
reboot it complains that a "Hyper transport sync flood occurred".

I found
https://lists.freebsd.org/pipermail/freebsd-stable/2012-January/065542.html
which seems to match but when I try the cpuset command mentioned there I
get an error:

; sudo cpuset -c -l 0 -x 58
cpuset: setaffinity: Invalid argument

Looks like the -c was invalid. After removing that I was informed -x 58
wasn't valid. Sure enough, there's no mpt0 or IRQ 58 on the host:

; vmstat -i
interrupt                          total       rate
irq17: ohci2                        8578          2
irq18: ohci3                         473          0
irq19: ohci0 ohci1+                 4924          1
irq24: mvs0                          457          0
irq32: mvs1                          453          0
irq38: mvs2                          451          0
irq46: mvs3                         8063          1
irq52: em0                        152354         35
irq53: em1                           140          0
irq68: mvs4                          450          0
irq76: mvs5                          454          0
cpu0:timer                        208311         48
cpu1:timer                         98318         23
cpu2:timer                        105704         24
cpu3:timer                        106202         24
Total                             695332        162

Looking around with some help from #freebsd on efnet I found mvs0-5
which are connected to the Marvel drive controllers on the host. I then
used
  ; sudo cpuset -l 0 -x ##
where I replaced ## with 24, 32, 38, 46, 68, and 76.

After rebuilding the zpool I started writing to it. It took a lot less
time to crash - I didn't even need to run zpool scrub - but instead of
completely locking up it just rebooted. I did not see reference to the
hyper transport problem while watching it boot but given the poor
performance of the serial console I can't be 100% sure it wasn't there.

So now I turn here to ask for guidance. Is anyone currently successfully
running 10.x on a x4500 and if so, how are you doing it? If not, how can
I get this working?

thanks,
nomad