Hyperledger Fabric v1.0 - multiple “orderers” for single channel

Question

The network configuration that is provided with the e2e_cli example has only one "orderer" container and a set of kafka/zookeeper containers.

My questions are:

• Q1: Is the single "orderer" some kind of architectural restriction of HLFv1.0 when single channel need to be created ?
• Q2: Is it possible to run multiple "orderers" for HA purposes when only one channel is used ?

the documentation suggests that multiple orderers can be used, but my understanding is that each "orderer" provide ordering service for single channel - is it right ?

Answer 1

Q1: Is the single "orderer" some kind of architectural restriction of HLFv1.0 when single channel need to be created ?

No, you can have more than 1 ordering service node.

Q2: Is it possible to run multiple "orderers" for HA purposes when only one channel is used ?

Yes. That was the intention of the kafka-based orderer - to have multiple instances of ordering service nodes all connect to a single fault tolerant service (kafka) that would do the ordering, and have them act as mediators to that service.

the documentation suggests that multiple orderers can be used, but my understanding is that each "orderer" provide ordering service for single channel - is it right ?

You can submit a transaction or pull a block from any of the orderers. They would go to the same kafka node that is the leader of that channel for that time. Also - orderers are multi-tenant regarding channels - orderers can service multiple channels.