[Users] Sane value for dcachesize

[Roman Haefeli]

Hi all

We're running a bunch of Containers on hostnodes that still have plenty
of free memory. Also, we monitor the user beancounters on the hostnodes
and it appears that the barrier for dcachesize is exceed by many
containers and this causes a warning in our monitoring system. 

Since there is no shortage of memory, I don't see why we should limit
the cache for the file system. Would there be a problem of setting much
higher value, say 30GB, for this parameter? Is there something one needs
to take care of when increasing DCACHESIZE?

Thanks,
Roman