Setting up a standby node with the same BLS key is forbidden
It is forbidden now to run multiple nodes using the same set of BLS keys. As we are moving towards full decentralization, external validators will become the shard leader and start to propose blocks. If one validator runs multiple nodes using the same set of valid keys, they may all become valid leaders when the key is rotated to this validator, in this case, the blockchain is experiencing a high risk of hard-fork as different valid leaders may propose different blocks. So, do not run redundant validator nodes anymore on the Harmony blockchain. This is also strictly forbidden on all PoS blockchains such as Ethereum 2, Cosmos.
For Cloud
Validator
Specs
Shard 0
Shard 1
Cloud provider CPU's are usually shared unless you specifically chose a dedicated CPU or opt for a dedicated bare metal server
Here is a list of Cloud Providers (August, 2020):
Check for instructions.
RPC / Explorer node Full Node
Same requirement as validator unless specified below:
Specs
Shard 0
Shard 1
RPC / Explorer node Archival Node
Same requirement as validator unless specified below:
Shard 0
Shard 1
For Raspberry Pi
Same as above for the type of node you wish to run
A Raspberry Pi 4 with a good Fan and Heat sinker elements will be required
Check for instructions.