While my Alpha PC164 with all filesystems on a raidframe mirror was
under a relatively light load (building a package), I got a the
following panic:

	panic: vref used where vget required, vp 0xfffffc00021a9868

The kernel trace was (hand copied):

	panic
	vref
	uvm_vnp_uncache
	ffs_truncate
	vfs_inactive
	vput
	handle_workitem_remove
	softdep_process_worklist
	sched_sync
	esigcode

Look familar?  I'm not putting in a PR, since the box locked up when I
tried to force a crash dump.  Since it has softdep in the backtrace,
I've now disabled them.  The box has been stable for ages with no
softdeps, and got the above panic within a fortnight of starting to use
them.  Once bitten, twice shy...

Also, I had a very hard time convincing the root filesystem to disable
softdeps.  Merely removing the ",softdep" from /etc/fstab was not
enough.  No matter what sequence of commands I tried in single user
mode, I couldn't get it to boot without softdeps on the root filesystem.
Some of the things I tried were:

	boot to single user
	mount -u -o nosoftdep /
	dumpfs /dev/rraid0a - shows "softdep enabled"
	reboot

	boot to single user
	(using a static tunefs with TUNEFS_SOFTDEP defined):
	/tunefs -n disable /dev/rraid0a
	dumpfs /dev/rraid0a - shows "softdep disabled"
	reboot
	softdeps enabled again!

what finally worked was

	boot off install floppy
	(/dev/wd0h starts 64 blocks after /dev/raid0a)
	mount -u -o nosoftdep /dev/wd0h /mnt
	umount /mnt
	reboot

Is there meant to be a simple way to disable softdeps on a root
filesystem?

Simon.
--
Simon Burge                            <simonb@wasabisystems.com>
NetBSD Sales, Support and Service:  http://www.wasabisystems.com/