[afnog] FreeBSD mirroring

[Brian Candler]

On Thu, Apr 27, 2006 at 06:15:52PM +0200, Phil Regnauld wrote:
>     10. That's it!  Check with gmirror status that it's rebuilding in the
>         background.
> 
>     Note: the underlying disk is ALWAYS available -- just remove
>     geom_mirror_load from the loader.conf, reboot, boot with -a (ask for
>     root device) and you can without problem access /dev/da0s1a for example,
>     but then the raid is broken...

Are there some unwritten assumptions here? e.g.

(1) that the last block of the original device does not contain any
important data; and
(2) that the filesystem will never need to write to the last block of the
device, after it has been shrunk by one block?

In other words, how can you be sure that this procedure is safe?

Regards,

Brian.