[Zope] Multiple ZODB for virtual hosts with ZEO

[Dieter Maurer]

David Pratt wrote at 2005-9-21 13:38 -0300:
> ...
If I wanted to configure with multiple zodb 
>for a single ZEO server you say there may be a possible downside in 
>requiring a single ZEO server per database instance further down the 
>road.  Is this something that is currently planned so I don't implement 
>something that will  not be supported later?

This was discussed on a zope mailing list (I think "zodb-dev at zope.org").
Please search the archives (via your favorite search engine).

>It could be also be a bit 
>of a problem since each ZEO server requires its own RAM.  RAM is a 
>valuable commodity.

ZEO is not very RAM hungry.

Only for packing, a higher amount of RAM is necessary.

>My goal is to ensure that customers I work with are working exclusively 
>in their own zodb.  It seems preferable for these zodb's to be 
>associated with a single ZEO server (instead of each zodb mounted in a 
>single zope instance) to make maintenance tasks smooth and handled 
>asynchronously.

Does this not speak for one ZEO server per customer?

   Imagine, you must restore a storage for one customer (because he
   destroyed its content).

   With a single ZEO server, you must bring it down to activate
   the backup. All your customers are affected.

   With a separate ZEO for each customer -- you bring
   down the ZEO for this customer. All others are unaffected.

>I realize that if resources were 
>unlimited, it would be best for a single ZEO server to use a single 
>zodb and have one or more ZEO clients.

Huch? I do not understand that argument.

   With unlimited resources, each customer had its own computer
   with its own ZEO and ZEO clients...


> ...
>I guess I see the possibility of single ZEO  for a number of virtual 
>hosted sites as a plus (since it means also that I could add additional 
>ZEO clients to provide more threads for serving the group of virtual 
>sites).

But for this, it does not matter whether you have one or
many ZEO servers...

-- 
Dieter