Based on the thread below (reading "legacy" as meaning "likely to be deprecated in later versions"), we have been working to extract ourselves from Master/Slave replication
Most of our collections need to be in two data centers (a read/write copy in one local data center: the disaster-recovery-site SolrCloud could be read-only). We also need redundancy within each data center for when one host or another is unavailable. We implemented this by having different SolrClouds in the different data centers; with Master/Slave replication pulling data from one of the read/write replicas to each of the Slave replicas in the disaster-recovery-site read-only SolrCloud. Additionally, for some collections, there is a desire to have local read-only replicas remain unchanged for querying during the loading process: for these collections, there is a local read/write loading SolrCloud, a local read-only querying SolrCloud (normally configured for Master/Slave replication from one of the replicas of the loader SolrCloud to both replicas of the query SolrCloud, but with Master/Slave disabled when the load was in progress on the loader SolrCloud, and with Master/Slave resumed after the loaded data passes QA checks). Based on the thread below, we made an attempt to switch to CDCR. The main reason for wanting to change was that CDCR was said to be the supported mechanism, and the replacement for Master/Slave replication. After multiple unsuccessful attempts to get CDCR to work, we ended up with reproducible cases of CDCR loosing data in transit. In June, I initiated a thread in this group asking for clarification of how/whether CDCR could be made reliable. This seemed to me to be met with deafening silence until the announcement in July of the release of Solr8.6 and the deprecation of CDCR. So we are left with the question whether we should expect Master/Slave replication also to be deprecated; and if so, with what is it expected to be replaced (since not with CDCR)? Or is it now sufficiently safe to assume that Master/Slave replication will continue to be supported after all (since the assertion that it would be replaced by CDCR has been discredited)? In either case, are there other suggested implementations of having a read-only SolrCloud receive data from a read/write SolrCloud? Thanks -----Original Message----- From: Shawn Heisey <apa...@elyograg.org> Sent: Tuesday, May 21, 2019 11:15 AM To: solr-user@lucene.apache.org Subject: Re: SolrCloud (7.3) and Legacy replication slaves On 5/21/2019 8:48 AM, Michael Tracey wrote: > Is it possible set up an existing SolrCloud cluster as the master for > legacy replication to a slave server or two? It looks like another option > is to use Uni-direction CDCR, but not sure what is the best option in this > case. You're asking for problems if you try to combine legacy replication with SolrCloud. The two features are not guaranteed to work together. CDCR is your best bet. This replicates from one SolrCloud cluster to another. Thanks, Shawn
