Re: SATA disk error and hang until "atacontrol reinit" ?

As a follow up, I had this happen again, without rebooting after running
"atacontrol reinit ata4".  That worked a few times, but the interval between
failed requests was very small... At some point, reiniting the channel
simply said "no devices attached" and I went and bought a new disk, fearing
the worst.  Placing that on the channel, I attempted "atacontrol reinit"
again and it still refused to see the new disk.  I tested both the new and
old disks with a different controller and they worked fine.  On the
suggestion of ##freebsd, I ran "atacontrol detach ata4" and "atacontrol
attach ata4"; the former completed, the latter produced this (via serial
console):

hydra# atacontrol attach ata4
ata4: [ITHREAD]
 60201-4533^[[2;2~Master:      no device present
Slave:       no device present
ast data access mmu miss   t                ra                p:
f
cpuid = 0

which I assume really meant to be "trap: fast data access mmu miss".  I
amn't sure what that means, but I have this lovely multi-gig core file
now... which is potentially of little utility since I get told "GDB can't
read core files on this machine." but if somebody wants something out of it,
just ask.

In any case, I powered the machine off, put the old disk back, and rebooted
and am now scrubbing the RAIDZ, but it sees the old disk just fine.

Suggestions?
--nwf;