Setting up sharding with different Server Hardware for Config Server and Shards

I am planning to upgrade from a 5 member replica set to Sharding and had a question on my Hardware.
Because the Config Server’s Replica Set does not require as much resources and won’t have as much a heavy load as the Shards - can I have a replica set using Previous Generation HP Hardware and disks - and have the Shards use best Generation Hardware and SSD’s and still have the best performance?
Also if you could refer me to backup processes for Sharded Clusters that would be great.

Kindest regards
Gareth Furnell

If you are absolutely certain about the following for your use-case:

then I do not see any reason why you could not

But only you would know for sure as it all depends on your use-case. You first have to determine for sure that for your use-case, the CS does indeed uses less resources. Testing is the only answer.

You did not mentioned if you would run all your shards on the same 5 machines that you already have or if you would add more. If you do not add more, then you would have to run multiple instances of mongod on the same machine. In most of cases, I do not think, I have no numbers to back that claim, that running multiple instances of mongod, provides the best performance. But your millage may differ.