We're trying to understand the best way to grow our Mongo installs.

Assuming an even distribution shard-key, so that it could shard to N servers effectively, Which would be a better strategy?

2 physical servers with 32GB each, or 32 physical servers with 2GB each?

The second scenario would make more CPUs available, and more disk spindles available, but it would mean that data is less likely to be adjacent on the same server, and that more data would require crossing the network.

Can you advise on which way, in general, is better to proceed?