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From Tomás Fernández Löbbe <tomasflo...@gmail.com>
Subject Re: From Solr3.1 to SolrCloud
Date Thu, 22 Nov 2012 15:39:21 GMT
>
> - I change my synonyms.txt on a solr node. How can i get zookeeper in sync
> and the other solr nodes without restart?
>

Well, you can upload the whole collection configuration again with zkClient
(included in the "cloud.scripts" section). see
http://wiki.apache.org/solr/SolrCloud#Getting_your_Configuration_Files_into_ZooKeeper
Other option, if you only want to upload one file is to write something
that communicate with zk with any of it's apis. I did this before Solr's
"zkClient" was committed and it is quite simple. Then, you can reload the
collection, which is like reloading all the cores for the collection in the
different nodes. See
http://wiki.apache.org/solr/SolrCloud#Managing_collections_via_the_Collections_API

>
> - I read something more about zookeeper ensemble. When i need to run with 4
> solr nodes(replicas) i need 3 zookeepers in ensemble(50% live). When
> zookeeper and solr are separated it will takes 7 servers to get it live. In
> the past we only needed 4 servers. Are there some other options because the
> costs will grow? 3 zookeeper servers sounds like overkill.
>

The number of Solr instances doesn't have to do with the number of ZK
instances that you need to run.  You can effectively run with only one zk
instance, the problem with this is that if that instance dies, then your
whole cluster will go down. So you can increase the number of zk instances.
When you create your Zookeeper ensemble, you declare the size of it (the
number of zk instances it will contain). When you run that ensemble,
Zookeeper requires that N/2+1 of the servers are connected. This means that
if you want your zk ensemble to survive one instance dying, you'll need at
least 3 ZK instances (if you have 2, and one dies, you still need 2 to
work, so it wont).

There has been some discussions these days in the list about this, but if
the number of physical servers is too much for you, you could run on the
same physical machine an instance of Solr and ZK.

Tomás

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