@abckdc In a 3-node cluster, all nodes are used for a combination of data and metadata e.g. there is no dedicated Witness. Now, if you don't need anywhere near 30TB (e.g. 20TB space is more than enough) and have enough compute resources in 2 nodes, you could run a 2-node + Witness - this is basically a VM running somewhere else.
Yes, a node can be replaced or another added and data resynced to it.
