CF disk slices?

[Harlan Stenn]

> Harlan Stenn wrote:
> > Can one put multiple slices on a CF disk?

> Sure.  Most BIOSes will treat a CF flash much like they would a USB
> device, and they'll be happy to see a MBR.

Hmmm - I can see the slices on a FreeBSD-4 machine but not on a
FreeBSD-5 machine.

> > I ran fdisk on one machine
> > and was able to carve up a CF disk with 4 slices (I want to boot one of
> > 4 different OSes on a soekris system).  There are other systems that
> > seem to indicate that a CF disk can only have 1 slice on it.

> Hmm.  You are perhaps not aware that flash memory can only do a relatively
> limited number of writes before failing (10K to perhaps 50K, if you've got a
> fancy CF card with write leveling and/or spare sectors)...?

Yup, and my plan is to slice the card, do a dd dump of a bootable OS to
one partition, and then do a dd dump of another bootable OS to the other
partions.

> Installing and updating multiple operating systems is contraindicated
> on such hardware not because it is not possible to do, but because the
> CF won't last very long under such a usage profile.

I'm even planning to netboot grub for this box so I can control which OS
boots without writing to the card.

> You should configure a CF-based system to operate with the filesystems
> mounted read-only most of the time, or at least turn off updating
> atime information.

That's the way they are set up - I even think the normal OS on that
copies things like root's homedir to a memory filesystem during the boot
and then mounts that somewhere for "live" use just to avoid writing to
the drive.  My goal is to have the CF disk be used in case I cannot do a
netboot.

H