The Algorand network is comprised of two distinct types of nodes, relays and non-relays. A participation node is a non-relay node that hosts one or more online accounts with valid participation keys.
As of the January 28 TestNet release, non-relay nodes can be configured to be archival or non-archival nodes. Archival nodes store the entire blockchain; non-archival nodes store only as many blocks as necessary to ensure progress. Thus, a non-archival node requires significantly less storage, generally less than a full day’s worth of blocks, and can reasonably bound its database size.
For example, after 36 hours, the TestNet archival ledger was 212.5MB, whereas the non-archival ledger was 9MB.
Currently, a relay node must be archival; a non-relay node may be archival or not.
A node is a valid relay node if two things are true:
- The node is configured to accept incoming connections on a publicly-accessible port (4161 by convention).
- The node's public IP address (or a valid DNS name) and assigned port are registered in Algorand's SRV records for TestNet.
Relay nodes are where other nodes connect. Therefore, a relay node must be able to support a large number of connections, and handle the processing load associated with all the data flowing to and from these connections. Thus, relay nodes require significantly more power than non-relay nodes.