[OpenAFS-devel] prdb format extension for extended authentication names

[Jeffrey Hutzelman]

On Fri, 2013-06-21 at 12:06 +0100, Simon Wilkinson wrote:
> On 10 Jun 2013, at 17:24, Benjamin Kaduk wrote:
> 
> > I have left out the idea of a UUID attached to the generic extended data for now.  I think that the main benefit from such a concept would be if operating in a mixed environment of new and old ptservers, or if it is necessary to revert to the old code for some reason.
> 
> At the moment, OpenAFS doesn't support running mixed dbserver
> environments. This is a hangover from the IBM days, but pretty much all
> of our documentation is clear that a dbserver upgrade requires a
> complete shutdown, upgrade, restart process. I don't think a UUID helps
> in enough of the edge cases to be worthwhile having. 
> 
> There are two things I think we should have to make this easier.
> Firstly, we should actually use the version number, and increase it
> each time there is a change made to a ubik database that isn't
> backwards compatible. Secondly, we should make sure that we don't end
> up with n^2 possible db formats. That means that we should never make
> the ubik database format dependent upon configure flags. That probably
> means that we should just turn on supergroups for everyone.

Unfortunately, that's a bit too simplistic.  It would be really bad if
someone were to upgrade dbservers, have a problem, and then be unable to
downgrade to a working version.  That means we have to be careful about
upgrades, avoid using new features unless/until an administrator has
enabled them, and provide tools for downgrading databases.

-- Jeff