lucene-solr-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Walter Underwood <wun...@wunderwood.org>
Subject Re: Minimum HA Setup with SolrCloud
Date Fri, 07 Dec 2012 00:51:53 GMT
What is the mystery? Two is not more than half of four. Therefore, two machines is not a quorum
for a four machine Zookeeper ensemble.

wunder

On Dec 6, 2012, at 4:50 PM, Jack Krupansky wrote:

> It's still an unresolved mystery, for now.
> 
> -- Jack Krupansky
> 
> -----Original Message----- From: Walter Underwood
> Sent: Thursday, December 06, 2012 7:30 PM
> To: solr-user@lucene.apache.org
> Subject: Re: Minimum HA Setup with SolrCloud
> 
> The Zookeeper ensemble knows the total size. It does not adjust it each time that a machine
is partitioned or down.
> 
> Two machines is not a quorum for a four machine ensemble.
> 
> Why do you think that the documentation would get this wrong?
> 
> wunder
> 
> On Dec 6, 2012, at 4:14 PM, Jack Krupansky wrote:
> 
>> But that is the context I was originally referring to - that with 4 zk you can lose
only one, that you can't lose two. So, if you want to tolerate a loss on one, 4 zk would be
the minimum... but then it was claimed that you COULD start with 3 zk and loss of one would
be fine. I mean whether you start with 4 and lose 2 or start with 3 and lose 1 is the same,
right?
>> 
>> -- Jack Krupansky
>> 
>> -----Original Message----- From: Yonik Seeley
>> Sent: Thursday, December 06, 2012 6:34 PM
>> To: solr-user@lucene.apache.org
>> Subject: Re: Minimum HA Setup with SolrCloud
>> 
>> On Thu, Dec 6, 2012 at 5:55 PM, Jack Krupansky <jack@basetechnology.com> wrote:
>>> I trust that you have the right answer, Mark, but maybe I'm just struggling
>>> to parse this statement: "the remaining two machines do not constitute a
>>> majority."
>>> 
>>> If you start with 3 zk and lose one, you have an ensemble that does not
>>> "constitute a majority".
>> 
>> I think you took that out of context.  They were talking about losing
>> 2 nodes in a 4 node cluster.
>> 
>> "For example, with four machines ZooKeeper can only handle the failure
>> of a single machine; if two machines fail, the remaining two machines
>> do not constitute a majority."
>> 
>> -Yonik
>> http://lucidworks.com
> 
> --
> Walter Underwood
> wunder@wunderwood.org
> 
> 
> 

--
Walter Underwood
wunder@wunderwood.org




Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message