Hi, I would start with one instance per host and add more shards to that one. As long as you stay below 32G heap this would be a preferred setup. It is a common mistake to think that you need more JVM heap than necessary. In fact you should try to minimize your heap and leave more free RAM for OS.
-- Jan Høydahl, search solution architect Cominvent AS - www.cominvent.com > 27. aug. 2018 kl. 05:09 skrev Wei <weiwan...@gmail.com>: > > Thanks Shawn. When using multiple Solr instances per host, is there any way > to prevent solrcloud from putting multiple replicas of the same shard on > same host? > I see it makes sense if we can splitting into multiple instances with > smaller heap size. Besides that, do you think multiple instances will be > able to get better CPU utilization on multi-core server? > > Thanks, > Wei > > On Sun, Aug 26, 2018 at 4:37 AM Shawn Heisey <apa...@elyograg.org> wrote: > >> On 8/26/2018 12:00 AM, Wei wrote: >>> I have a question about the deployment configuration in solr cloud. When >>> we need to increase the number of shards in solr cloud, there are two >>> options: >>> >>> 1. Run multiple solr instances per host, each with a different port and >>> hosting a single core for one shard. >>> >>> 2. Run one solr instance per host, and have multiple cores(shards) in >> the >>> same solr instance. >>> >>> Which would be better performance wise? For the first option I think JVM >>> size for each solr instance can be smaller, but deployment is more >>> complicated? Are there any differences for cpu utilization? >> >> My general advice is to only have one Solr instance per machine. One >> Solr instance can handle many indexes, and usually will do so with less >> overhead than two or more instances. >> >> I can think of *ONE* exception to this -- when a single Solr instance >> would require a heap that's extremely large. Splitting that into two or >> more instances MIGHT greatly reduce garbage collection pauses. But >> there's a caveat to the caveat -- in my strong opinion, if your Solr >> instance is so big that it requires a huge heap and you're considering >> splitting into multiple Solr instances on one machine, you very likely >> need to run each of those instances on *separate* machines, so that each >> one can have access to all the resources of the machine it's running on. >> >> For SolrCloud, when you're running multiple instances per machine, Solr >> will consider those to be completely separate instances, and you may end >> up with all of the replicas for a shard on a single machine, which is a >> problem for high availability. >> >> Thanks, >> Shawn >> >>
