FAQ
Hi,

I have a question regarding NameNode.addBlock() function.
I see that it makes sure that the previous block is replicated before you
assign an additional block.
I wonder why it checks penultimate block rather than ultimate block ?
Is it because it would take some time for the immediately previous block to
be replicated?

Thanks,
Sangmin

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  • Dhruba Borthakur at Feb 23, 2009 at 6:31 pm
    Hi Sangmin,

    your assumtion is right. addBlock() allocates an ew block only if the
    penultimate block has reached the minimum replication factor. The
    blockreceived messages from the immediately previous block might take a
    while to be sent by the datanode and processed by the namenode.

    thanks,
    dhruba

    On Mon, Feb 23, 2009 at 4:50 AM, Sangmin Lee wrote:

    Hi,

    I have a question regarding NameNode.addBlock() function.
    I see that it makes sure that the previous block is replicated before you
    assign an additional block.
    I wonder why it checks penultimate block rather than ultimate block ?
    Is it because it would take some time for the immediately previous block to
    be replicated?

    Thanks,
    Sangmin

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groupcommon-dev @
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postedFeb 23, '09 at 12:50p
activeFeb 23, '09 at 6:31p
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Sangmin Lee: 1 post Dhruba Borthakur: 1 post

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