ZFS Panic after freebsd-update

[Jeremy Chadwick]

On Mon, Jul 01, 2013 at 09:10:45PM +0300, Andriy Gapon wrote:
> on 01/07/2013 20:04 Jeremy Chadwick said the following:
> > People are operating with the belief that "ZFS just
> > works", when reality shows "it works until it doesn't"
> 
> That reality applies to everything that a man creates with a purpose to work.
> I am not sure why you are so over-focused on ZFS.
> Please stop spreading FUD.  Thank you.

The issue is that ZFS on FreeBSD is still young compared to other
filesystems (specifically UFS).  Nothing is perfect, but FFS/UFS tends
to have a significantly larger number of bugs worked out of it to the
point where people can use it without losing sleep (barring the SUJ
stuff, don't get me started).  I have the same concerns over other
things, like ext2fs and fusefs for that matter -- but this thread is
about a ZFS-related crash, and that's why I'm "over-focused" on it.

A heterogeneous (UFS+ZFS) setup, rather than homogeneous (ZFS-only),
results in a system where an admin can upgrade + boot into single-user
and perform some tasks to test/troubleshoot; if the ZFS layer is
broken, it doesn't mean an essentially useless box.  That isn't FUD,
that's just the stage we're at right now.  I'm aware lots of people have
working ZFS-exclusive setups; like I said, "works great until it
doesn't".

So, how do you kernel guys debug a problem in this environment:

- ZFS-only
- Running -RELEASE (i.e. no source, thus a kernel cannot be rebuilt
  with added debugging features, etc.)
- No swap configured
- No serial console

-- 
| Jeremy Chadwick                                   jdc at koitsu.org |
| UNIX Systems Administrator                http://jdc.koitsu.org/ |
| Making life hard for others since 1977.             PGP 4BD6C0CB |