I have an SBS 2011 domain at a single site. I had previously added a second domain controller for redundancy (including DNS) so that when the SBS server needs rebooting the network is uninterrupted. SBS is a virtual on a hyperv host, and the secondary DC was also a hyperv guest on another physical hyperv host.
The secondary died however and while I was able to restore it still caused issues in the domain. I was able to demote it using normal means eventually, and dcdiag reports things are fine on the SBS server.
I'd like to re-promote the server now, and I'm wondering if it avoid issues like this in the future if it would be better to make this a read only domain controller (RODC). The site is very small, just one location, and only rarely are changes to AD made. Also given how SBS works (the SBS server must hold the FSMO roles) it seems like it would simplify things while still allowing some redundancy.
Does this sound like a reasonable approach or is there a reason I should have a second RW domain controller?