[TYPO3] one backend interface for multiple installations?

[Bing Du]

Hi,

We're running typo3 4.0.4 to host multiple sites on one installation.  It
works great.  On the other hand, it could also imply single point failure.
 It has happened to us that even a missing single ';' in
typo3conf/localconf.php can bring all the sites down.  The impact was
significant.  Also we allow web editors to create PHP content elements. 
So there are some concerns about running all the sites on one single
database.  We want to prevent one site's error from affecting other sites,
that is.  I'm thinking to create a separate database to host future new
sites.  If I understand correctly, the backend interface only works with
one database.  I'll have to have another backend interface to connect to
another database that hosts another set of web sites.   But in out
situation, these two sets of websites need to share contents, for ex.
news.  It would be good that one backend interface can see multiple page
trees with each one associating with different database.  Any thoughts or
comments?

Thanks in advance,

Bing