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From Todd Lipcon <t...@cloudera.com>
Subject Re: Expectation during Rollback after a partially failed Upgrade .. Should DELTA be visible ?
Date Mon, 30 May 2011 16:25:50 GMT
Hi Sreehari,

Which versions are you using for this test?

In step 1 below, how does the upgrade fail? Can you provide specific steps
to reproduce?

Smells like a bug to me, if I understand the scenario correctly.

-Todd

On Mon, May 30, 2011 at 5:29 AM, Sreehari G <sreehari.g@huawei.com> wrote:

>  Hi all ,
>
> What is the expectation in the following scenario :
>
> Namenode has 3 name dirs configured ..
> 1) Namenode upgrade starts - Upgrade fails after 1st directory is upgraded
> (2nd and 3rd dir is left unchanged ..)
> 2) Namenode starts
> 3) Namenode shutdown and rollbacked
>
> Are the new changes done meant to be visible ? With current implementation
> , after a rollback new changes are visible .. Is this expected ??
>
> As per my observation , since Namenode is saving the latest image dir(the
> upgraded 1st dir since checkpointtime is incremented during upgrade for this
> dir) will be loaded and saved to all dirs during loadfsimage ..
>
> But if a ROLLBACK is done , the 1st dir will be rolled back (the older copy
> becomes current and its checkpointtime is now LESS than other dirs ..) and
> others left behind since they dont contain previous .. Now during
> loadfsimage , the 2nd dir will be selected since it has the highest
> checkpoint time and saved to all dirs (including 1st ) .. Now due to this ,
> the new changes b/w UPGRADE and ROLLBACK DELTA  present in 2nd dir gets
> reflected even after ROLLBACK ..
>
> Is this expected ? I ask this since :
>
> 1) this is not the case with a SUCCESSFULL Upgrade/Rollback (New changesare  lost
> after rollback).. &
> 2) In Hadoop-702 (DFS Upgrade Proposal) , FSStateTransition7.htm says {
> r0. if previous directory does not exist then fail rollback } , but it
> continues in the current implementation ..
>
>
>
> Regards ,
>
> Sreehari
>
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>
>
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> Domlur
> Bangalore
> www.huawei.com
>
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-- 
Todd Lipcon
Software Engineer, Cloudera

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