Approach 2 is sufficient. You do have to insure that you don't copy over the write.lock file however as you may not be able to start replicas if that's there.
There's a relatively little-known third option. You an (ab)use the replication API "fetchindex" command, see: https://cwiki.apache.org/confluence/display/solr/Index+Replication to pull the index from Cloud B to replicas on Cloud A. That has the advantage of working even if you are actively indexing to Cloud B. NOTE: currently you cannot _query_ CloudA (the target) while the fetchindex is going on, but I doubt you really care since you were talking about having Cloud A offline anyway. So for each replica you fetch to you'll send the fetchindex command directly to the replica on Cloud A and the "masterURL" will be the corresponding replica on Cloud B. Finally, what I'd really do is _only_ have one replica for each shard on Cloud A active and fetch to _that_ replica. I'd also delete the data dir on all the other replicas for the shard on Cloud A. Then as you bring the additional replicas up they'll do a full synch from the leader. FWIW, Erick On Fri, Aug 25, 2017 at 6:53 PM, Wei <weiwan...@gmail.com> wrote: > Hi, > > In our set up there are two solr clouds: > > Cloud A: production cloud serves both writes and reads > > Cloud B: back up cloud serves only writes > > Cloud A and B have the same shard configuration. > > Write requests are sent to both cloud A and B. In certain circumstances > when Cloud A's update lags behind, we want to bulk copy the binary index > from B to A. > > We have tried two approaches: > > Approach 1. > For cloud A: > a. delete collection to wipe out everything > b. create new collection (data is empty now) > c. shut down solr server > d. copy binary index from cloud B to corresponding shard replicas in > cloud A > e. start solr server > > Approach 2. > For cloud A: > a. shut down solr server > b. remove the whole 'data' folder under index/ in each replica > c. copy binary index from cloud B to corresponding shard replicas in > cloud A > d. start solr server > > Is approach 2 sufficient? I am wondering if delete/recreate collection > each time is necessary to get cloud into a "clean" state for copy binary > index between solr clouds. > > Thanks for your advice!
