Erick, Thank you for your response. Yup, when I said it is not possible to have a cross continent data center replica, I meant that we never ever want to do that because of the latency.
What I was hoping is that I could have Solr cloud in my DataCentre A (DC-A) and get all the benefits of sharding ( scaling/parallel computing) and failover redundancy within the same data center. If I could then have a read-only replica (with no guaranteed consistency of course ) of this entire cloud in my DataCenter B (DC-B), that would make my reads over DC-B faster without making my writes slow. To clarify, all the writes were going to go against DC-A only. The read-only cluster in DC-B could also be made the master in case the entire DC-A went down. The DC-B wouldn't be guaranteed to be in sync with the DB-A master but in my use case I could live with that. Seems like that is no possible out-of-the-box if I am using Solr 4.0+ in the cloud mode. It is either Solr Coud or cross data center read only replica. Can't do both at the same time. I think that is what you confirmed as well. If I have it wrong, please let me know. Also, any thoughts on the most easy way to accomplish the read-only replica of the entire solr cloud cluster? Thanks! Tikoo From: Sandeep Tikoo Sent: Saturday, September 27, 2014 9:43 PM To: 'solr-user@lucene.apache.org' Subject: SolrCould read-only replicas Hi- I have been reading up on SolrCloud and it seems that it is not possible to have a cross-datacenter read-only slave anymore but wanted to ask here to be sure. We currently have a pre Solr 4.0 installation with the master instance in our US mid-west datacenter. The datacenter in Europe has read-replicas which pull data using solr.ReplicationHandler. We wanted to upgrade to SolrCloud. As far as I have been able to figure out, with SolrCloud you cannot have a read-only replica anymore. A replica has to be able to become a leader and writes against all replicas for a shard have to succeed. Because of the a strong consistency model across replicas, it seems that replicas cannot be across datacenters anymore. So my question is, how can we have a read-ony replica in a remote datacenter in Solr 4.0+ similar to pre Solr 4.0? Is it not possible anymore without doing it all yourself? cheers, Tikoo
