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From: Sanjay Radia <sradia@yahoo-inc.com>
To: Konstantin Boudnik <cos@apache.org>
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Subject: Re: [Discuss] Merge federation branch HDFS-1052 into trunk
Date: Wed, 27 Apr 2011 07:03:05 -0700
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On Apr 26, 2011, at 10:40 PM, Konstantin Boudnik wrote:

> Oops, the message came out garbled. I meant to say
>
> I assume the outlined changes won't prevent an earlier version of  
> HDFS from
> upgrades to the federation version, right?


Yes absolutely. We have tested upgrades .
Besides our ops will throw us out of the window if we even hint that  
there isn't an
automatic upgrade for the next release :-)

sanjay
>
> Thanks in advance,
>  Cos
>
> On Tue, Apr 26, 2011 at 17:59, Konstantin Boudnik <cos@apache.org>  
> wrote:
>> Sanjay,
>>
>> I assume the outlined changes won't an earlier version of HDFS from
>> upgrads to the federation version, right?
>>
>> Cos
>>
>> On Tue, Apr 26, 2011 at 17:26, Sanjay Radia <sradia@yahoo-inc.com>  
>> wrote:
>>>
>>> Changes to the code base
>>>  - The fundamental code change is to extend the notion of block id  
>>> to now
>>> include a block pool id.
>>> - The  NN had little change, the protocols did change to include  
>>> the block
>>> pool id.
>>> - The DN code did change. Each data structure is now indexed by  
>>> the block
>>> pool id -- while this is a code change, it is architecturally very  
>>> simple
>>> and low risk.
>>> - We also did a fair amount of cleanup of threads used to send  
>>> block reports
>>> - while it was not strictly necessary to do the cleanup we took  
>>> the extra
>>> effort to pay the technical debt. As Dhruba recently noted, adding  
>>> support
>>> to send block reports to primary and secondary NN for HA will be  
>>> now much
>>> easier to do.
>>