[OpenAFS-devel] Re: AFS ... or equivalent ...

[Rick C. Petty]

On Wed, Jan 16, 2008 at 01:48:52PM -0500, Jeffrey Hutzelman wrote:
> --On Monday, January 14, 2008 02:23:47 PM +0000 Robert Watson 
> <rwatson@FreeBSD.org> wrote:
> 
> >I'd like very much to get at least the kernel parts of an AFS client into
> >the base system.
> That may well be realistic for arla, though I believe there was a period 
> for a while where the kernel/arlad interface was evolving to support 
> features like chunking.  I pay only superficial attention to arla-drinkers, 
> so I don't know what the status of any of that is; for that, you'd have to 
> ask someone who is actively involved in arla development (I believe there 
> are some such people on this list).
> 
> It is unlikely ever to happen for OpenAFS, in which virtually all of the 
> cache manager code is in-kernel and most of it is cross-platform.  Trying 
> to pull the OpenAFS cache manager into the FreeBSD kernel would be 
> equivalent to forking OpenAFS; what you'd get would work and would keep up 
> with FreeBSD, but it would be unlikely to keep up with OpenAFS.
> 
> The "let's just slurp everything into the main distribution so we don't 
> have to worry about stable interfaces" approach is really poor.  It 
> encourages bad engineering practice among people maintaining the main 
> distribution, discourages innovation and extension by others, and generally 
> doesn't scale.  It's far better to either attempt to maintain stable 
> external interfaces to the VFS and VM subsystems, or else admit that you 
> don't have the resources to do so given the relatively small number of 
> external users, in which case you almost certainly also don't have the 
> resources to keep on top of updates to something like OpenAFS.
> 
> In the long run, I'm guessing that the OpenAFS cache manager evolves more 
> quickly than FreeBSD's VFS interface, which makes pulling the CM into the 
> kernel tree a losing battle.  If you disagree, by all means fork that part 
> of AFS (or get someone else to do so) and see what happens (AFS's 
> user/kernel and RPC interfaces are both fairly stable, so forking just the 
> kernel parts should be mostly feasible).
> 
> -- Jeff
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-- 


-- Rick C. Petty