Hello again Justin, Are there any plans to drop the traditional Artemis quorum voting mechanism for the pluggable quorum provider configuration? Any idea when it will become officially stable?
Thank you, Aaron Steigerwald -----Original Message----- From: Steigerwald, Aaron Sent: Friday, April 8, 2022 11:46 AM To: users@activemq.apache.org Subject: RE: [EXTERNAL]:Re: Journal corruption caused by split brain? Hello Justin, Thank you for the thorough explanation. How much better is ZooKeeper at mitigating split brain than having a 3+ node cluster? Why would ZooKeeper be better than quorum voting at dealing with network issues that would cause split brain? Thanks again, Aaron -----Original Message----- From: Justin Bertram <jbert...@apache.org> Sent: Thursday, April 7, 2022 11:18 PM To: users@activemq.apache.org Subject: [EXTERNAL]:Re: Journal corruption caused by split brain? [CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.] ________________________________ It's not clear exactly what is meant here by "corruption," but I think it's probably the wrong word to describe the issues caused by split-brain. The brokers should be able to read all the data in the journals no problem. The actual problems are more related to potential duplicate consumption or missed messages. Regarding duplicate consumption, consider 2 JMS consumers listening on a queue on the master broker. Those consumers would be competing for the same messages such that each message would only be consumed once (i.e. by either consumer). However, once split brain occurs you could potentially have a consumer on the same queue on *each* broker. In that case, they could each receive the same message since they were no longer competing with each other. Regarding missed messages, consider a non-durable JMS topic subscriber. While it's connected to the master it receives every message sent to the topic. However, once split brain occurs the producer might send messages to the broker where the subscriber isn't connected which means it wouldn't get those messages. In short, the data on each broker should stay 100% in-tact from a technical stand-point. The problem is more in the realm of "irreconcilable differences" for the applications connected to the brokers. The simplest way to mitigate split-brain is to use a shared-store. However, if a shared-store is not viable for your use-case the next best solution is to integrate with ZooKeeper via the pluggable quorum vote replication configuration [1]. Justin [1] https://activemq.apache.org/components/artemis/documentation/latest/ha.html#pluggable-quorum-vote-replication-configurations On Thu, Apr 7, 2022 at 9:53 PM Steigerwald, Aaron <asteigerw...@brandesassociates.com.invalid> wrote: > Hello, > > My colleague has read that split brain can cause journal corruption in > a master/slave network replication scenario. Is anyone aware if this > is possible with current versions of Artemis? > > Thank you, > Aaron Steigerwald >
