hadoop-zookeeper-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Flavio Junqueira <...@yahoo-inc.com>
Subject Re: Zookeeper WAN Configuration
Date Sat, 25 Jul 2009 14:55:27 GMT
Todd, you can try using flexible quorums to implementing what your  
requesting. You can simulate the behavior I described of observers by  
setting the weight of the server to zero. Please check the  
documentation at:

	http://hadoop.apache.org/zookeeper/docs/r3.2.0/zookeeperAdmin.html

Check under "Cluster Options" options like group and weight.

-Flavio


On Jul 24, 2009, at 5:03 PM, Todd Greenwood wrote:

>
> In the future, once the Observers feature is implemented, then we  
> should
> be able to deploy zk servers to both the DC and to the pods...with all
> the goodness that Flavio mentions below.
>
>
> -----Original Message-----
> From: Flavio Junqueira [mailto:fpj@yahoo-inc.com]
> Sent: Friday, July 24, 2009 4:50 PM
> To: zookeeper-user@hadoop.apache.org
> Subject: Re: Zookeeper WAN Configuration
>
> Just a few quick observations:
>
> On Jul 24, 2009, at 4:40 PM, Ted Dunning wrote:
>
>> On Fri, Jul 24, 2009 at 4:23 PM, Todd Greenwood
>> <toddg@audiencescience.com>wrote:
>>
>>> Could you explain the idea behind the Observers feature, what this
>>> concept is supposed to address, and how it applies to the WAN
>>> configuration problem in particular?
>>>
>>
>> Not really.  I am just echoing comments on observers from them that
>> know.
>>
>
> Without observers, increasing the number of servers in an ensemble
> enables higher read throughput, but causes write throughput to drop
> because the number of votes to order each write operation increases.
> Essentially, observers are zookeeper servers that don't vote when
> ordering updates to the zookeeper state. Adding observers enables
> higher read throughput affecting minimally write throughput (leader
> still has to send commits to everyone, at least in the version we have
> been working on).
>
>>
>>> """
>>> The ideas for federating ZK or allowing observers would likely do
>>> what
>>> you
>>> want.  I can imagine that an observer would only care that it can  
>>> see
>>> it's
>>> local peers and one of the observers would be elected to get updates
>>> (and
>>> thus would care about the central service).
>>> """
>>> This certainly sounds like exactly what I want...Was this
>>> introduced in
>>> 3.2 in full, or only partially?
>>>
>>
>> I don't think it is even in trunk yet.  Look on Jira or at the
>> recent logs
>> of this mailing list.
>
> It is not on trunk yet.
>
> -Flavio
>


Mime
View raw message