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From "Anthony Ikeda" <Anthony.Ik...@cardlink.com.au>
Subject RE: Active-Active Performance
Date Tue, 25 May 2010 02:12:37 GMT
Thanks Hemanth,

In regards to different locations of the HADOOP home this is low
priority more for testing not production. I was trying to install HADOOP
for testing over 2 machines with only a Windows XP machine running
Cygwin and a Mac running Darwin. Not a priority.

In regards to my last question about operating in a detached fashion, we
are trying to factor in what happens when the link between both sites is
cut. Will both sites operate independently until the connection is
re-established? Is there any particular setup required to ensure we can
cover this scenario or is it an out-of-the-box feature?

Anthony


-----Original Message-----
From: Hemanth Yamijala [mailto:yhemanth@gmail.com] 
Sent: Tuesday, 25 May 2010 12:08 PM
To: general@hadoop.apache.org
Subject: Re: Active-Active Performance

Anthony,

I'm new to Hadoop and I've been given the task to see how we might
utilise
> Hadoop and HBase to implement an Active-Active site layer for sharing
> information across a distributed application.
>
>
>
> I've been able to:
>
> *         Install and get Hadoop running on a single node and am in
the
> process of configure a 2 node setup.
>
> *         Install HBase on a single node and create a table and
mapping as
> well as insert data into the system
>
>
>
> Once I've got the mutli-node configured I hope to run some tests as
well.
>
>
>
> I've noticed that trying to start Hadoop in distributed mode, the
slave
> will ssh to the master to start it as well (bin/start-all.sh) provided
the
> same path is setup on the remote machine.
>
>
>
> Questions:
>
> Can I configure the system IF the Hadoop installation is not in the
same
> location per machine?
>

I would think configuring and managing such a system would get very
complex
- for e.g. if you'll want to add nodes to expand in future. You would
also
not be able to take advantage of the very helpful scripts that come with
Hadoop. Is there a reason why you want to do this ?

> If the master node goes down (say due to electrical fault or system
fault)
> how do the slave nodes react? Will they continue to run? Will the
nodes be
> back in sync once the master starts again?
>

Hadoop slaves will continue. They will enter a retry loop trying to
connect
to the master until it comes up. In doing so, they could fill up log
files
very fast though. If the master starts with the same configuration,
(same
host, ports), they should be able to connect and resume.

> Would I require a particular configuration to ensure that both our
sites
> can operate within the cluster as well as in a detached fashion (due
to
> maintenance or network issues)?
>
>
>
I did not quite follow this. Can you explain a little more about how you
want to setup your system ?

Thanks
Hemanth

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