Hi all, I believe at leas at Solr 8x or previous there isn't any way to solve this problem.
You can have 5, 7 or thousands of zookeepers to improve the HA but you cannot dynamic add or remove zookeepers from the list. So if you have for example two servers with 2 and 3 zookeepers and one of this nodes fall dawn you will have problems on two ways, pair number of zookeepers up if the server that have fail down have 3 zoos and problems of leader election between the zookepeers, Anyone knows if there are any way to solve this problem? Or if in 9x versions there are any improve about it? Thanks a lot Kind regards. ________________________________ David Martín Nieto Analista Funcional Calle Cabeza Mesada 5 28031, Madrid T: +34 667 414 432 T: +34 91 779 56 98| Ext. 3198 E-mail: dmart...@viewnext.com | Web: www.viewnext.com ________________________________ [https://mail.google.com/mail/u/0?ui=2&ik=72317294cd&attid=0.0.2&permmsgid=msg-f:1662155651369049897&th=171129c229429f29&view=fimg&sz=s0-l75-ft&attbid=ANGjdJ_o0Ds8_P8d7W-csq2mmc6mBGQy9hSjXsGEv15RXUutalCYzg3HQB3CByE2swcJkH3yRaLwrXkr1G81F9FpfqcPlbpRoZcainmsJjviLoypusuKOxCnOw97zuo&disp=emb] ________________________________ De: Eric Pugh <ep...@opensourceconnections.com> Enviado: martes, 21 de mayo de 2024 18:12 Para: users@solr.apache.org <users@solr.apache.org> Asunto: Re: SolrCloud behavior when Zookeeper has lost a quorum. [EXTERNO] Este correo electrónico se envió desde fuera de la organización. No haga clic en enlaces ni abra archivos adjuntos a menos que reconozca al remitente y sepa que el contenido es seguro I’ve had a lot of luck using the bats testing infrastructure to try out “what if” situations with Solr to see what actually happens. For example, I tested out classic leader/follower replication works when your leader is a single node solr cloud server and your follower is a totally separate single node cloud server! You may want to write some bats test that simulate these situations to confirm/deny what folks say “should” happen. They would be great to have for integration/regression testing as well. > On May 21, 2024, at 11:30 AM, Matt Kuiper <kuipe...@gmail.com> wrote: > > Thanks for the responses! > > Shawn, > > I believe I understood that Zookeeper does not actually handle the request. > Thanks for the clarification as I did not word it properly. > > More precisely, will a SolrJ CloudSolrClient work for the purpose of > querying SolrCloud if the ZK host list it is configured with represents a > Zookeeper ensemble that has lost its quorum? > > My goal is to learn if this SolrJ client (configured via zkhost list) can > reliably query a SolrCloud even when the ZK ensemble has lost its quorum. > > I have heard that Zookeeper will go into a read-only mode if quorum is > lost. Put another way, will the SolrJ cloud client still be able to talk > to ZK to discover the URLs required to get > to Solr and serve queries (at least will the solrj client be given the > latest state from the remaining ZK nodes for what was last written to > Zookeeper)? > > Our company is reviewing HA/DR scenarios for SolrCloud and I am > investigating if a SolrCloud that has lost its ZK quorum can provide any > value for Solr queries, and how to characterize accuracy of any search > results. > > Thanks for any further information you can provide. > > Matt > > On Mon, May 20, 2024 at 9:02 PM Shawn Heisey <apa...@elyograg.org.invalid> > wrote: > >> On 5/20/2024 17:46, mtn search wrote: >>> Will a SolrJ client connection (configured with a ZKhost list) to a >>> SolrCloud still work for querying a SolrCloud when the Zookeeper ensemble >>> has lost its quorum, but some ZK nodes remain up? I understand that >>> indexing will not work. >>> >>> Follow-on - will the Solr query work to the same SolrCloud if the query >> is >>> sent directly to a Solr node rather than to Zookeeper? >> >> Requests to SolrCloud such as queries or indexing do not go through ZK, >> ever. >> >> The SolrJ cloud client talks to ZK to discover the URLs required to get >> to Solr and which of them are online at any given moment. ZK is used as >> a central database to coordinate the cluster, it does not handle requests. >> >> Thanks, >> Shawn >> >> _______________________ Eric Pugh | Founder | OpenSource Connections, LLC | 434.466.1467 | http://www.opensourceconnections.com <http://www.opensourceconnections.com/> | My Free/Busy <http://tinyurl.com/eric-cal> Co-Author: Apache Solr Enterprise Search Server, 3rd Ed <https://www.packtpub.com/big-data-and-business-intelligence/apache-solr-enterprise-search-server-third-edition-raw> This e-mail and all contents, including attachments, is considered to be Company Confidential unless explicitly stated otherwise, regardless of whether attachments are marked as such.
