Help with Replication

[gfngfn256]

Question, is a 2 node cluster reliable if I run a 3rd node as a QDevice?

Yes, that's what a QDevice is for.

 

[deanfourie]

Yes, that's what a QDevice is for.

What if the QDevice goes down? No HA right

 

[gfngfn256]

What if the QDevice goes down? No HA right

If the QDevice fails/ goes down your cluster will carry on happily, as long as another node doesn't go down.
You need to read up what HA is & isn't. And what Quorum is about.