I wondered if it's possible to have a separate database for each portal in DNN?

If I was going to create 3 different websites, I would probably want to create 3 different databases - one for each site.

I'm new to DNN and apologies if this has been asked and answered many times before.

Technically they're not portals with separate databases, they're completely separate DNN installations.  And many clients will want this rather than a database shared with others.

Jeff

Having multiple portals in one IIS website and DB is fine for non-business/hobby/personal/family websites, or for a case when you want to create a website that does seperation by portal for a single client.
So there are some benefits to having the ability to create multiple portals, but that doesn't mean it is the best thing to do.

You mention moving the different portals to different Databases, but also consider that if your different portals share the same codebase and application space that it is just as "bad" of a sharing scenario as sharing the database. IMO it is actually worse to have them sharing the same application space.  There are many reasons for this:

• They will not be sand-boxed at the physical file system so access to the file system through FTP can not be granted.
• They will share the same scheduler background threads which cause redundant processes and lockups.
• They will share the same IIS configuration which is important for SSL, and many other low level settings that are usually needed to be set differently (IIS7 does make this better).
• They share the same caching space (both physical and memory).
• Upgrades will affect all portals at the same time (this could be a good thing, but it is usually bad).
• One bad module or mis-configuration can bring down all your portals.

Those are just a few but serious issues that I can think of off the top of my head.  So in short having multiple portals can be very nice for a single client, but it is probably best to completely seperate any business clients.