RE: 2 Server Cluster !?

2008-11-25 Thread Krishna Sankar (ksankar)
Valdimir,

Good scenario. As Mahadev points out quorum and HA are slightly
different animals. If I am correct, the Quorum also has the correctness
attribute, which needs more than one server - the 2n+1 requirement.

Looks like what you are looking for is the traditional HA
primitive with an active-active configuration. You might still be able
to use Zookeeper, with leader election and state management, but you
will need at least 3 processes - (at least)one Zookeeper, two server
processes.

Cheers

P.S : May be we should capture this pattern in ZooKeeper. (May be we
already have, as I am coming up to speed)
|-Original Message-
|From: Mahadev Konar [mailto:[EMAIL PROTECTED]
|Sent: Tuesday, November 25, 2008 9:27 AM
|To: zookeeper-user@hadoop.apache.org
|Subject: Re: 2 Server Cluster !?
|
|Hi Valdimir,
| Its not possible to run a Zookeeeper quorum of 2 such that if one dies
|the
|other one continues to run and server clients. The whole idea of
|zookeeper
|is its high reliability and the guarantee's it provides.
|http://wiki.apache.org/hadoop/ZooKeeper/Tao
|
|So, its not possible to run zookeeper as you state.
|
|mahadev
|
|
|On 11/25/08 7:33 AM, "Vladimir Bobic" <[EMAIL PROTECTED]> wrote:
|
|> Ahoy everyone,
|>
|> I'm interested to know if there is anyway to run 2 servers cluster in
|which:
|>  - if 1 server fails other one continues to serve clients.
|>  - when failed server is back, force elections to favored server
|>  I'm aware that there is possibility for both servers to work
|> independently not knowing for each other,
|> difference that could immerge is not issue.
|>
|> Regards,
|> Vladimir



Re: 2 Server Cluster !?

2008-11-25 Thread Mahadev Konar
Hi Valdimir,
 Its not possible to run a Zookeeeper quorum of 2 such that if one dies the
other one continues to run and server clients. The whole idea of zookeeper
is its high reliability and the guarantee's it provides.
http://wiki.apache.org/hadoop/ZooKeeper/Tao

So, its not possible to run zookeeper as you state.

mahadev


On 11/25/08 7:33 AM, "Vladimir Bobic" <[EMAIL PROTECTED]> wrote:

> Ahoy everyone,
> 
> I'm interested to know if there is anyway to run 2 servers cluster in which:
>  - if 1 server fails other one continues to serve clients.
>  - when failed server is back, force elections to favored server
>  I'm aware that there is possibility for both servers to work
> independently not knowing for each other,
> difference that could immerge is not issue.
> 
> Regards,
> Vladimir