Hello,

I'm looking for community's _opinion_ for a potential setup for a SAAS
startup that's using mongodb as it's main storage...

There will be multiple databases (each user will have a database).
Initially there will be only 1 dedicated server (with about 20GB of RAM), 2
x HDD (RAID 1).
3 node replica set - 1 data, 1 arbiter and 1 hidden data (to take regular
backups to an external machine).
I don't know how many users I want to handle yet with this setup, but I'm
planning to implement some constraints (e.g. N req/sec or N req/day)

What do you think? Of course I'm aware of the chance that entire server
will crash, but besides that, should I expect decent performance,
durability as long working set fits in RAM? And of course I'll do my
testing too, but I wonder if I'm missing any detail that is better to take
care if it from the beginning than deal with it later.

I already have a small website with not a lot of traffic that runs on 1
node mongodb with regular backups and I have never had problems(it's been
running for 1.5 years now), but this time i will expect to be under much
havier load.

Thank you in advance.

PS: Sorry, it turned out to be longer than I hoped...