[OpenAFS] All limitations of OpenAFS

[Tom Keiser]

On Tue, Jan 26, 2010 at 7:49 AM, Lars Schimmer <l.schimmer@cgv.tugraz.at> wrote:
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> Hi!
>
> For a new EU project we want to setup a OpenAFS cell.
> As we could hit some limitations of OpenAFS, I would like to collect all
> known limitations of current OpenAFS systems (1.5.70 on windows and
> 1.4.11 on linux that is).
> I know of:
>
> - -one RW copy of a volume
> - -max 6 RO copies from one volume

Are you referring to the number of repsites that can be represented in
the vldb, or the number of distinct clones supported within a volume
group?

repsites:  IIRC, vldb version 4 supports 13 repsites (so a max of 12
RO sites w/o BK; 11 w/ a BK repsite)

clones:  This depends on whether your backing store is namei or inode.
 For namei, the safe limit is five volumes within a volume group.
Thus, in the typical case you get one RW and four clones.  Note that
you can go beyond this limit (IIRC the true limit is 35), but there
must be DV overlap for every vnode (or clone operations will fail) --
each vnode (irrespective of differences in uniquifier) on namei can
have at most five divergent versions at any given point in time.

Cheers,

-Tom