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From "Jain, Prem" <Premanshu.J...@netapp.com>
Subject Rack Awareness behaviour - Loss of rack
Date Tue, 07 Feb 2012 19:28:47 GMT

I have  rack awareness configured and seems to work fine.  My default rep count is 2.  Now
I lost one rack  due to switch failure. Here is what I observe

HDFS  continues to write in the existing available rack. It still keeps two copies of each
block, but now these blocks are being stored in the same rack.

My questions:

Is this the default HDFS behavior ?
What happens when the failed rack in back online ? Will HDFS automatically rewrite blocks
to the other rack ?
Or - Do I have to run the rebalance to make that happen ?

Thanks in advance.

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