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From "Dhruba Borthakur" <dhr...@gmail.com>
Subject Re: Hadoop 1.0 Compatibility Discussion.
Date Thu, 23 Oct 2008 18:02:28 GMT
Hi Sanjay,

Ok, let me understand the terminology.
  -- Versions 1.0 and versions 2.0 are "major" releases, maybe occur
once every year
  -- Versions 1.2 and 1.3 are minor releases, maybe occurs once every 2 months
   -- Versions 2.4.5 and 2.4.6 are "dot" release.

Is my understanding correct?

>don't you want disk format compatibility to be for both major and minor release changes
as I stated earlier?

Disk formats can change for both major and minor releases but not for
dot release. And the hadoop code should handle the required disk
format upgrades and downgrades transparently. This issue, by itself,
should have no impact on pre-existing FileSystem APIs.

Does this make sense?

thanks,
dhruba

On Wed, Oct 22, 2008 at 9:04 AM, Sanjay Radia <sradia@yahoo-inc.com> wrote:
>
>
>
> On Oct 20, 2008, at 11:44 PM, Dhruba Borthakur wrote:
>>
>> 3. HDFS disk format can change from 1.x to 1.y release and is
>> transparent to user-application. A cluster when rolling back to 1.x
>> from 1,y will revert back to the old disk format.
>
> Dhruba don't you want disk format compatibility to be for both major and
> minor release changes as I stated earlier?
> I don't think it is acceptable to break data format across major releases.
>
>
> Q. do we want disk upgrade to be supported across arbitrary number of
> releases? For example we allowed the crc upgrade for
> approx 4 releases in the past.
>
>
>

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