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From Erick Erickson <>
Subject Re: Solrcloud with Master/Slave
Date Thu, 04 Jan 2018 16:09:44 GMT
Whoa. I don't think you should be doing this at all. This really
appears to be an XY problem. You're asking "how to do X" without
telling us what the problem you're trying to solve is (the Y). _Why_
do you want to set things up this way? A one-time synchronization or
to keep both collections in sync?

Cross Data Center Replication (CDCR) is designed to keep two separate
collections in sync on an ongoing basis.

If this is a one-time deal, you can manually issue a replication API
"fetchindex" command. What I'd do in that case is set up your
collection B with each shard having exactly one replica (i.e. a leader
and no followers). Do the fetch and verify that your new collection is
as you want it then ADDREPLICA to build out your redundancy.


On Thu, Jan 4, 2018 at 8:01 AM, Sundaram, Dinesh
<> wrote:
> Thanks Shawn for your prompt response. Assume I have solrcloud A server with 1 node runs
on 8983 port and solrcloud B server with 1 node runs on 8983, here I want to synch up the
collection between solrcloud A and B using the below replication handler. Is this advisable
to use at the solrcloud B ?
> <requestHandler name="/replication" class="solr.ReplicationHandler" >
>     <lst name="slave">
>         <str name="masterUrl">http://solrcloudA:8983/solr/${}/replication</str>
>         <str name="pollInterval">00:00:20</str>
>     </lst>
> </requestHandler>
> Dinesh Sundaram
> MBS Platform Engineering
> Mastercard
> -----Original Message-----
> From: Shawn Heisey []
> Sent: Tuesday, January 2, 2018 5:33 PM
> To:
> Subject: Re: Solrcloud with Master/Slave
> On 1/2/2018 3:32 PM, Sundaram, Dinesh wrote:
>> I have spun up single solrcloud node on 2 servers.
> This makes no sense.  If you have two servers, then you probably have more than a single
>> tried to synch up the data b/w those servers via zookeeper
> This is not done with zookeeper.  SolrCloud should handle it automatically.  SolrCloud
uses the zookeeper database to *coordinate* keeping machines in sync, but it's Solr that does
the work, not zookeeper.
> This makes even less sense when taken in context with the previous sentence.  If you
only have a single node, then you can't possibly sync between them.
>> but didn’t work well due to out of memory issues, ensemble issues with
>> multiple ports connectivity. So had to move to Master slave
>> replication b/w those 2 solrcloud nodes. I couldn’t find any issues so
>> far. Is this advisable? Because I’m wondering that looks like mixing
>> up solrcloud and master/slave replication.
> If you're getting OOME problems, then whatever program threw the OOME most likely needs
more heap.  Or you need to take steps to reduce the amount of heap that's required.  Note
that this second option might not actually be possible ... increasing the heap is probably
the only option you have.  Since version 5.0, Solr has shipped with the default heap set to
512MB, which is extremely small.  Most users need to increase it.
> You can't mix master-slave replication and SolrCloud.  SolrCloud takes over the replication
feature for its own purposes.  Trying to mix these is going to cause you problems.  You may
not run into the problems immediately, but it is likely that you would run into a problem
eventually.  Data loss would be possible.
> The latest versions of Solr have new SolrCloud replication types that closely mimic the
old master-slave replication.
> Perhaps you should start over and describe what you've actually seen -- exactly what
you've done and configured, and how the results differed from your expectations.  Precise
commands entered will be helpful.
> Thanks,
> Shawn
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