Re: [9fans] KFS Crash

["Russ Cox" <rsc@plan9.bell-labs.com>]

	1. If rio crashes is there a way to kill
	   rio and get back to the shell?

Not really.

	2. Given that I could, what diagnostics
	   could I run to identify the problem?
	3. Is there a way to repair the disk at this point?

I rarely see kfs get that hosed.  Are you sure
the root is from: got the right file system?

I'd try booting an install floppy and using it
as a rescue disk: ignore the install process,
draw yourself a new window, and try to start kfs
manually:

	disk/kfs -f /dev/sdC0/fs
	mount /srv/kfs /n/kfs

and maybe you'll get a bit farther.

There's almost always a way to repair the disk, depending
on how much energy you're willing to devote to it.
I have a clumsy C program that tries to pull
out textual data from broken kfs file systems
if you need something that wasn't backed up.

	4. Given that you don't have much faith
	   in kfs and some of us are using it
	   exclusively on our standalone terminals,
	   what sort of maintainance, such as
	   disk/kfscmd check, should we be doing?

One method is to set up two file systems and run
check say once a month.  When you start getting
things like bad tags, ream the other file system
and copy your data over; repeat.

For the most part, kfs is stable.  It gets unstable
fairly fast if you frequently don't "disk/kfscmd halt"
before shutting down, or if you crash your kernels a lot
(implies the first, but usually a bigger problem
since you can die during heavy disk i/o).

Nothing's set in stone but I think one hope for the
fabled file server rewrite is to have kfs build
from the same sources, which may at least exercise it
more.

Russ