[Zope] Zope's scalability across multiple web servers

[Michael Bernstein]

Jason Spisak wrote:
> 
> > Beyond the fact that this may not be a good idea, you might want to
> > store the postings in Zope, but the moderation score on the FS, as it is
> > likely to get overwritten A LOT (especially by moderation bots). You run
> > the slight risk of a given moderation being overwritten
> 
> Please forgive my ignorance, but could you explain the essencial difference
> between writing to the ZODB and a Filesystem Backend.  I'm just not getting
> why...

Basically, the ZODB is optimized in design for many reads and few
writes, and the filesystem is not. This means that in many-write
situations, the ZODB is working much harder than usual, and performance
of the site will go down faster than under an equivalent number of
reads.

> > statistically it should even out with as many 'up' moderations being
> > discarded accidentally as 'down' ones.
> 
> Is it because there is no locking?

Yes.

> > And you prevent Zope from
> > thrashing with many tiny committed transactions mucking up the 'Undo'
> > tab.
> 
> I definately understand that part.  I really appreciate this BTW.  It's an
> area of the Zope scope (;-) that I have thought about for a while(storage).

I beleive that this tradeoff (transactional integrity vs. efficient
writes) would be made irrelevant if the FS in question was either
ReiserFS or the IRIX Journalling FS, but I don't really know enough
about either to be certain.

HTH,

Michael Bernstein,
Information Architect.