[Ocfs2-devel] 256 node limit

[Bruce Schwartz <bruce.schwartz@gmail.com>]

Thanks. From looking at the code it appears that the maximum number of nodes 
are controlled by some #defines (OCFS2_NODE_MAP_MAX_NODES, O2NM_MAX_NODES) 
and that bumping the number up to something like 300 should be a simple 
matter. There is a note in the code that reads: "if we need more, we can do 
a kmalloc for the map" which I would guess addresses the case where you'd 
want thousands of nodes.

Is my reading correct? And would it be a bad idea to try to set up a 300+ 
node OCFS2 system?

Thanks,
Bruce

On 7/5/05, Sunil Mushran <Sunil.Mushran@oracle.com> wrote:
> 
> It's actually 255. Yes, that doc needs to be updated.
> 
> No, the algorithms did not play much role in setting this limit.
> Guess, can say the limit is part arbitrary, part practical.
> (That extra byte adds up pretty quickly.)
> 
> Bruce Schwartz wrote:
> 
> > Hi all --
> >
> > In the "what's new in OCFS2" document at
> > 
> http://oss.oracle.com/projects/ocfs2/dist/documentation/ocfs2-whats-new.txt
> > it says that the 256 node limit is a software limit and could be
> > lifted. Why is that limit there? Are there some algorithms that
> > don't scale nicely with larger number of nodes? I'm guessing that
> > there is more to it than saving a byte of RAM in a few data structures.
> >
> > Thanks,
> > Bruce
> >
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> >
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>
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