2 Server Cluster !?

classic Classic list List threaded Threaded
3 messages Options
Reply | Threaded
Open this post in threaded view
|

2 Server Cluster !?

Vladimir Bobic
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
Reply | Threaded
Open this post in threaded view
|

Re: 2 Server Cluster !?

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" <[hidden email]> 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

Reply | Threaded
Open this post in threaded view
|

RE: 2 Server Cluster !?

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
<k/>
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:[hidden email]]
|Sent: Tuesday, November 25, 2008 9:27 AM
|To: [hidden email]
|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" <[hidden email]> 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