Both "legacy" and "SolrCloud" clusters are search server clusters. Seen from far enough, they look the same.
In "legacy" the management code is elsewhere (developed by the client operating the cluster, running on other machines using a diferent logic and potentially another DB than Zookeeper) whereas in "SolrCloud" the management code is embedded in the search server(s) code and it happens that (currently) this code relies on Zookeeper. I see SolrCloud as a "managed cluster" vs. legacy that would be "Self managed" by the client, or "U manage" (non managed when looking at it from the Solr codebase perspective). Same idea as coordinated vs uncoordinated basically. I don't know why but I prefer "managed". Ilan On Thu, Aug 6, 2020 at 5:49 PM Cassandra Targett <casstarg...@gmail.com> wrote: > On Aug 6, 2020, 10:22 AM -0500, Gus Heck <gus.h...@gmail.com>, wrote: > > WRT the name "uncoordinated mode" I fear it could be read (or even become > known as) as "clumsy mode" which is humorous but possibly not what we're > going for :) > > > I had also considered “non-coordinated”, and prefer it but couldn’t > articulate why. The association of “uncoordinated" with clumsiness might be > what was bugging me. > > I'd perhaps suggest Cluster mode for SolrCloud though I'm not entirely > sure if Legacy Solr (in curren parlance) is not a "cluster" too, cluster > being a somewhat vague term. However Clustered Mode and Legacy Mode seem > more on target. I think "Legacy" could be changed since we're not really > planning on abandoning it (are we?), but > > > One can have a cluster and not run SolrCloud. I think from an operations > perspective, several servers all running Solr is considered a cluster, no > matter what tools are being used to get them to talk to each other. > > I think “Legacy” (also used today already in some contexts) is problematic > because there aren’t plans to abandon it. Also “Legacy replication” is > pretty close to exactly what PULL replicas use to poll leaders and pull new > index segments when needed. IOW, it’s not “legacy”, it’s very actively > being used in a growing number of clusters. That might be an implementation > detail users aren’t aware of, but I feel the term is really lacking mostly > in that it just doesn’t say anything besides “it’s older”. > > the adjective there SHOULD communicate reduced functionality because there > are plenty of features that are cloud (cluster) only. > > > In my view, the reduced functionality of non-SolrCloud clusters is mostly > around coordination of requests, leader election, configs, and other > similar automated activities one does manually otherwise. So, I feel that > sort of proves my point - a word that conveys lack of coordination is a > good option for what it’s called. If there is a better antonym for > “coordinated”, I’m all for considering it but haven’t yet been able to > think of/find one. > > I think it’s important to think about what differentiates the two ways of > managing a Solr cluster and derive the naming from that. What features of > SolrCloud don’t exist in the non-SolrCloud approach? What words help us > generalize those gaps and can any of them be an appropriate name? > > > -Gus > > > On Thu, Aug 6, 2020 at 10:27 AM Cassandra Targett <casstarg...@gmail.com> > wrote: > > The work in SOLR-14702 has left us with some awkward phrasing (which is > still better than what it was) around non-SolrCloud clusters that I've > offered to help fix. > > > I think we've struggled for years to find a good name for non-SolrCloud > clusters and we've used a number of variations: "legacy replication" (which > it isn't, since PULL replicas use the same thing), "Standalone mode" (which > it isn't because it's a cluster), now "leader/follower mode" (which could > be confusing because SolrCloud has leaders). > > > Yesterday I thought about what really differentiates a SolrCloud cluster > and a non-SolrCloud cluster and it occurred to me that a key difference is > the former is coordinated by ZooKeeper, while the latter is not. That led > me to think that perhaps "coordinated mode" can someday be a better > replacement for the term "SolrCloud", while "uncoordinated mode" could be a > replacement today for all these other non-SolrCloud mode variations. > > > I've opened https://issues.apache.org/jira/browse/SOLR-14716 and will > create a branch for work in progress, but before I forge too far ahead, I > want to draw attention to it first to give a chance for discussion so we're > in agreement. > > > Thanks, > > Cassandra > > > > -- > > http://www.needhamsoftware.com (work) > > http://www.the111shift.com (play) > >
