RFC: Project geom-events

[perryh at pluto.rain.com]

Lev Serebryakov <lev at freebsd.org> wrote:

> >> GPT _must_ be placed twice -- at first and last sectors
> >> (really, more than one sectors). By standard. Secondary
> >> copy must be at end of disk. Period.
> > Then, "by standard" GPT cannot coexist with GLABEL. Such setup
> > should be disallowed, or at least big nasty message that you
> > have just shoot yourself in the leg should be output. (period)
> Ok, maybe adding check to geom_part, that it is used on rank-1
> provider (whole disk) is not so bad idea. But it then raise
> question how to install FreeBSD on software mirror, what is
> useful.

To install FreeBSD on a gmirrored disk, use MBR (or "dangerously
dedicated" BSD label) instead of GPT.  (This is one reason why
BSD label and MBR should not be considered obsolete.)

If you want to use gmirror and *have* to use GPT, e.g. if you
have a (hypothetical) BIOS which will not boot from MBR, mirror
the individual partitions instead of the whole disk.  Granted
that is more trouble, both to set up initially and to replace
a failed drive.