Help! :( ZFS panic on boot, importing pool after server crash.

[Dr Josef Karthauser]

Hi, I'm a bit at the end of my tether.

We had a ZFS panic last night on a machine that hosts all my mail and web; it was rebooted and it now panics mounting the ZFS root filesystem.

The call stack info is:

	solaris assert: ss == NULL, file: /usr/src/sys/modules/zfs/../../cddl/contrib/opensource/uts/common/fs/zfs/space_map.c, line: 109

	kdb_backtrace
	panic
	space_map_add
	space_map_load
	metaslab_activate
	metaslab_allocate
	zio_dva_allocate	
	zio_execute
	taskqueue_run_locked
	taskqueue_thread_loop
	fork_exit
	fork_trampoline

I can boot from the live DVD filesystem, but I can only mount the pool read-only without getting the same kernel panic.  This is with FreeBSD 9.0.

The machine is remote, and I don't have access other than through a DRAC console port (so I can't cut and paste; sorry for the poor stack trace).

Is anyone here in the position to advice me how I might process to get this machine mounting and running again in multi-user mode?

Thanks so much.
Joe

p.s. the config, btw, is a ZFS mirror on two ad devices. It's got a ZFS root file system.