Depreciate and remove gbde

[Perry Hutchison]

Anton Shterenlikht <mexas at bris.ac.uk> wrote:

> I use gbde.
> Can switch to geli, if required,
> but please provide detailed instructions
> for switching before removing gbde.

Such instructions would presumably be included in the UPDATING
entry.

An additional consideration:  If there is no convert-in-place
mechanism -- i.e. the only way to convert a gbde FS to geli is to
backup, wipe, and restore (thus involving considerable downtime)
-- it will give some unknown number of production users a strong
motivation to freeze at [last version of FreeBSD to include gbde
support].