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From Chris Collins <chris_j_coll...@yahoo.com>
Subject Re: changing node's rack
Date Sat, 26 Mar 2011 21:28:56 GMT
Darren, people don't necessarily make things rack aware for performance.  Consider if you have
a rack of datanodes and all your block replicas  on nodes in that rack. If you have a switch,
power strip failure you would be down.  You are also able to provision in data centers two
circuits so by placing racks on different circuits reduces your chances of having downtime
if their is a power failure.  The power case of course you can also handle by buying more
expensive hw that has dual power supplies straddling the two circuits.

C 
On Mar 26, 2011, at 2:00 PM, <darren@ontrenet.com> wrote:

> IMHO, any effort spent trying to squeeze a gain from rack awareness is a
> waste of time. High speed networks & Moore's Law pretty much make the
> notion obsolete faster than any benefit (if there is one) can catch up to.
> 
> Not an answer to your question though. I realize that.
> 
>> What is the best way to change the rack of a node?
>> 
>> I have tried the following: Killed the datanode process. Changed the
>> rackmap
>> file so the node && and ip address entry reflect the new rack and I do a
>> '-refreshNodes'. Restarted the datanode.  But it seems the datanode is
>> keep
>> getting register to the old rack.
>> 
>> --
>> --- Get your facts first, then you can distort them as you please.--
>> 
> 


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