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From "Taeho Kang" <tka...@gmail.com>
Subject Question on relocation of Hadoop cluster
Date Thu, 04 Oct 2007 01:28:06 GMT
Hello all.

Due to limited space in current datacenter, I am trying to move my Hadoop
cluster to a new datacenter.
In the new datacenter, each machine will keep its hostname, but each will be
assigned to a new ip address.
We should be able to edit our DNS to assign existing hostnames to new ip
addresses.

My understanding is that namenode keeps track of a datanode with an ip
address, not a hostname.
(According to the description found on for "private String hostName" in
DatanodeInfo.java class)

Thus, the datanode / block info will be obsolete if the Hadoop cluster is
moved unless we do modify all the datanode / block info in the namenode....

The solutions that I can think of right now is...
1. modify all the datanode / block info : quite a risky work, i guess.
2. Have some "buffer" servers and have the data moved to there, and then to
the moved cluster in the new datacenter : but then it would require some
machines with lots of free storage and very careful planning.

Any comments on my solutions or any other suggestions will be welcomed!
Thank you all in advance.

Regards,

Taeho

p.s. Any future plan to hava the datanode info with a hostname instead of an
ip address?
Also, what was the motivation behind using an ipaddress instead of a
hostname to identify datanodes?

-- 
Taeho Kang [tkang.blogspot.com]
Software Engineer, NHN Corporation, Korea

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