[Zope] zeo cache-size tuning - number of obj. vs MB

[Gaute Amundsen]

Hi

What's the difference between the to cache-size settings here?
I've not been able to find a good description to guide me in finding the
right values.

<zodb_db main>
  mount-point /
  cache-size 10000          1.
  <zeoclient>
    server foo:9080
    storage main   
    name zeostorage  
    var $INSTANCE/var
    cache-size 20MB          2.
  </zeoclient>
</zodb_db>

As far as I've been able to determine, the second one 2. refers to a
separate cache at the zeo connection level.

Running 9 zeo clients (2.7.9) like this on a frontend with 4G ram,
varnish, apache, and haproxy. Tethering on the edge of too much
swapping. Needing to cut down..

Would it be better to spend all the memory on 1?
Is there a good way to find a balance?

Regards

Gaute Amundsen