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From lei liu <liulei...@gmail.com>
Subject Re: same edits file is loaded more than once
Date Mon, 05 Nov 2012 09:46:42 GMT
I research FSEditLog.loadFSEdits method, I find OP_ADD and OP_CLOSE
opration first  delete inode(call  FSDirectory.unprotectedDelete method),
then re-add inode(call FSDirectory.unprotectedAddFile method),  so if NN
read one OP_ADD transaction log and add one inode to namespace  for the
operation, when next time NN read the same transaction log form same edits
file,NN first delete the inode , then add same inode to namespace again,
So  I think this is no harmful,even if the same transaction log is loaded
more than once.

If my understand is wrong, welcom everyone to point it out.



2012/11/4 lei liu <liulei412@gmail.com>

> I am using hadoop0.20.2, now I want to use HDFS HA function.  I research
> AvatarNode. I find if the StandbyNN do checkpoint fail, when next time the
> StandbyNN do checkpoint, the same edits file is loaded again.  Can same
> edits file be loaded more than once in hadoop0.20.2?
> if not, what is the harm?
> Thanks,
> LiuLei

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