gmirror existing installation?

[Oles Hnatkevych]

Hello, freebsd-geom gurus.

There's a simple way of gmirroring existing installation.

> sysctl kern.geom.debugflags=16           # allow writing to a live filesystem
> gmirror label -v gm0 /dev/ad0
> # edit /etc/fstab, chane to /dev/mirror/gm0... slices
> # add "geom_mirror_load=YES" to /boot/loader.conf
> # reboot
> gmirror insert gm0 /dev/ad1

I just wonder if may cause any problems.
I see that "sysinstall" when told "A" to use whole disk reserves for
some reason some extra space at the end of the ad0, so there won't be
a problem with last-sector metadata. But I see that the ad0/ad1
geometry and the gm0 geometry is quite different in number of
cylinders and heads. Since the original system was labeled according
to one "mediasize", and now label "lives" on another "mediasize" (that
should be less in size) I wonder if the above method of mirroring existing
installation is 100% correct? And yet the MBR partition table was
created using another "units"...


-- 
Best wishes,
 Oles