__consumer_offsets & __transaction_state topics have ReplicationFactor: 1

[Chris Peart]

Hi,

We have a kafka production cluster that was setup with the defaults for 
__consumer_offsets & __transaction_state topics.

Is there a way to increase the replication factor from 1 to 3 using the 
kafka-reassign-partitions tool?

We are also replacing our 4 brokers with new brokers, this has been 
completed so we now have an 8 broker cluster and have migrated all the 
topics to the new brokers using the reassign tool except for the 
__consumer_offsets & __transaction_state topics.

We stopped kafka on the old brokers today but all out consumers failed 
due to the __consumer_offsets & __transaction_state topics residing on 
the old brokers.

I'm thinking we should could move the __consumer_offsets & 
__transaction_state topics to the now brokers using the reassign tool, i 
have done this on our dev platform and all is good. If you think this is 
good idea we can then can stop kafka on the old nodes and then work on 
the replication factoron the new nodes?

The problem i have is how do we change the replication factor to 3 after 
we migrate the __consumer_offsets & __transaction_state topics?

Thanks in advance.

Chris