On 11/9/2018 1:58 PM, David Hastings wrote:
I personally like standalone solr for this reason, i can tune the indexing "master" for doing nothing but taking in documents and that way the slaves dont battle for resources in the process.
SolrCloud can be set up pretty similar to this if you're running 7.5. You set things up so each collection has two TLOG replicas and the rest of them are PULL.
SolrCloud doesn't have master and slave in the same way as the old architecture. There are no single points of failure if the hardware is set up correctly. But because PULL replicas cannot become leader, they are a lot like slaves. Solr 7.5 and later can configure a preference for different replica types at query time. So with the setup described above, you tell it to prefer PULL replicas. If all the PULL replicas were to die, then SolrCloud would use whatever is left.
Let's say that you set up a collection so it has two TLOG replicas and four PULL replicas. You could have the TLOG replicas live on a pair of servers with SSD drives and less memory than the other four servers that have PULL replicas, which could be running standard hard drives. Queries love memory, indexing loves fast disks. The preference that indicates PULL replicas would keep the queries so they are running only on the four machines with more memory.
The reason that you want two TLOG replicas instead of one is so that if the current leader dies, there is another TLOG replica available to become leader.
Thanks, Shawn
