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From Visioner Sadak <visioner.sa...@gmail.com>
Subject Re: Multidata center support
Date Thu, 05 Sep 2013 08:03:40 GMT
Hi friends

hello baskar i think rack awareness and data center awareness are different
and similarly nodes and data centers are different things from hadoops
perspective but ideally it shud be same i mean nodes can be in different
data centers right but i think hadoop doesnt not  replicate data across
data centers i am not sure abt this (can anyone please comment on this).....

federation can provide different namenodes so you can create independent
clusters for example one cluster at one data center
and another cluster at a different  data center..... but if hadoop can
replicate across data centers then we need only one federation cluster for
all data centers :)...are any of you guys using a single federation cluster
across multiple data centers in production  for example

CASE--1

one cluster federation/data centers at  US/Europe---------------(if hadoop
can replicate across data centers )

NN1 ------US       DN1 ----US
NN2 ------Europe DN2 -----Europe

In this case data can be replicated to DN1 and DN2

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CASE--2

two independent cluster federation/data centers at
 US/Europe--------------(if hadoop cannot replicate across data centers )

cluster 1
cluster 2

NN1 ------US       DN1 ----US                                  NN2
------Europe DN2 -----Europe


In this case data cannot be replicated to DN2 or vice versa


*Can anyone clarify which will be the right and optimal case for hadoop
---------------------------------------------------------:)*





On Wed, Sep 4, 2013 at 2:20 AM, Baskar Duraikannu <
baskar.duraikannu@outlook.com> wrote:

> Rahul
> Are you talking about rack-awareness script?
>
> I did go through rack awareness. Here are the problems with rack awareness
> w.r.to my (given) "business requirment"
>
> 1.  Hadoop , default places two copies on the same rack and 1 copy on some
> other rack.  This would work as long as we have two data centers. if
> business wants to have three data centers, then data would not be spread
> across. Separately there is a question around whether it is the right thing
> to do or not. I have been promised by business that they would buy enough
> bandwidth such that each data center will be few milliseconds apart (in
> latency).
>
> 2. I believe Hadoop automatically re-replicates data if one or more node
> is down. Assume when one out of 2 data center goes down. There will be a
> massive data flow to create additional copies.  When I say data center
> support, I should be able to configure hadoop to say
>      a) Maintain 1 copy per data center
>      b) If any data center goes down, dont create additional copies.
>
> Above requirements that I am pointing will essentially move hadoop from
> strongly consistent to a week/eventual consistent model. Since this changes
> fundamental architecture, it will probably break all sort of things...
> Might not be possible ever in Hadoop.
>
> Thoughts?
>
> Sadak
> Is there a way to implement above requirement via Federation?
>
> Thanks
> Baskar
>
>
> ------------------------------
> Date: Sun, 1 Sep 2013 00:20:04 +0530
>
> Subject: Re: Multidata center support
> From: visioner.sadak@gmail.com
> To: user@hadoop.apache.org
>
>
> What do you think friends I think hadoop clusters can run on multiple data
> centers using FEDERATION
>
>
> On Sat, Aug 31, 2013 at 8:39 PM, Visioner Sadak <visioner.sadak@gmail.com>wrote:
>
> The only problem i guess hadoop wont be able to duplicate data from one
> data center to another but i guess i can identify data nodes or namenodes
> from another data center correct me if i am wrong
>
>
> On Sat, Aug 31, 2013 at 7:00 PM, Visioner Sadak <visioner.sadak@gmail.com>wrote:
>
> lets say that
>
> you have some machines in europe and some  in US I think you just need the
> ips and configure them in your cluster set up
> it will work...
>
>
> On Sat, Aug 31, 2013 at 7:52 AM, Jun Ping Du <jdu@vmware.com> wrote:
>
> Hi,
>     Although you can set datacenter layer on your network topology, it is
> never enabled in hadoop as lacking of replica placement and task scheduling
> support. There are some work to add layers other than rack and node under
> HADOOP-8848 but may not suit for your case. Agree with Adam that a cluster
> spanning multiple data centers seems not make sense even for DR case. Do
> you have other cases to do such a deployment?
>
> Thanks,
>
> Junping
>
> ------------------------------
> *From: *"Adam Muise" <amuise@hortonworks.com>
> *To: *user@hadoop.apache.org
> *Sent: *Friday, August 30, 2013 6:26:54 PM
> *Subject: *Re: Multidata center support
>
>
> Nothing has changed. DR best practice is still one (or more) clusters per
> site and replication is handled via distributed copy or some variation of
> it. A cluster spanning multiple data centers is a poor idea right now.
>
>
>
>
> On Fri, Aug 30, 2013 at 12:35 AM, Rahul Bhattacharjee <
> rahul.rec.dgp@gmail.com> wrote:
>
> My take on this.
>
> Why hadoop has to know about data center thing. I think it can be
> installed across multiple data centers , however topology configuration
> would be required to tell which node belongs to which data center and
> switch for block placement.
>
> Thanks,
> Rahul
>
>
> On Fri, Aug 30, 2013 at 12:42 AM, Baskar Duraikannu <
> baskar.duraikannu@outlook.com> wrote:
>
> We have a need to setup hadoop across data centers.  Does hadoop support
> multi data center configuration? I searched through archives and have found
> that hadoop did not support multi data center configuration some time back.
> Just wanted to see whether situation has changed.
>
> Please help.
>
>
>
>
>
> --
> *
> *
> *
> *
> *Adam Muise*
> Solution Engineer
> *Hortonworks*
> amuise@hortonworks.com
> 416-417-4037
>
> Hortonworks - Develops, Distributes and Supports Enterprise Apache Hadoop.<http://hortonworks.com/>
>
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