FreeBSD upgrade woes (8.3 -> 8.4)

[David Noel]

On 7/11/13, David Noel <david.i.noel at gmail.com> wrote:
> I've been directed to the freebsd-fs list, so hopefully I'm in the
> right place for this question.
>
> I have 4 servers I'm upgrading from 8.3 to 8.4. Two of them went
> without a hitch, two of them blew up in my face. The only difference
> between the two is the ones that worked have a 2-disk ZFS mirror and
> the ones that didn't have a 4-disk ZFS striped mirror configuration
> (RAID10). They both use the GPT.
>
> After installworld && installkernel they made it through boot, but
> right before the login prompt I'm getting a panic and stack dump. The
> backtrace looks something like this (roughly):
>
> 0 kdb_backtrace
> 1 panic
> 2 trap_fatal
> 3 trap_pfault
> 4 trap
> 5 calltrap
> 6 vdev_mirror_child_select
> 7 vdev_mirror_io_start
> 8 zio_vdev_io_start
> 9 zio_execute
> 10 arc_read
> 11 dbuf_read
> 12 dbuf_findbp
> 13 dbuf_hold_impl
> 14 dbuf_hold
> 15 dnode_hold_impl
> 16 dmu_buf_hold
> 17 zap_lockdir
>
> Does anyone have any idea what went wrong?
>
> Does anyone have any suggestions on how to get past this?
>
> Is there any more information I could provide to help debug this?
>
> Thanks,
>
> David

I replaced the kernel with the one on the 8.4 memstick and it booted
just fine. I then built and installed a kernel without using the j
flag to test the idea suggested on freebsd-questions@ that it could
have been a buggy kernel caused by j>1. It booted without problem.
Maybe there's something to this -j >1 causing buggy kernels rumor? At
any rate, I don't think I'll try buildkernel with j>1 again.