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From YIMEN YIMGA Gael <gael.yimen-yi...@sgcib.com>
Subject RE: Need to evaluate a cluster
Date Thu, 10 Jul 2014 08:43:01 GMT

What does « 1.3 for overhead » mean in this calculation ?


From: Mirko Kämpf [mailto:mirko.kaempf@gmail.com]
Sent: Wednesday 9 July 2014 18:09
To: user@hadoop.apache.org
Subject: Re: Need to evaluate a cluster


if I follow your numbers I see one missing fact: What is the number of HDDs per DataNode?
Let's assume you use machines with 6 x 3TB HDDs per box, you would need about 60 DataNodes
per year (0.75 TB per day x 3 for replication x 1.3 for overhead / ( nr of HDDs per node x
capacity per HDD )).
With 12 HDD you would only need 30 servers per year.
How did you calculate the number of 367 datanodes?


2014-07-09 17:59 GMT+02:00 YIMEN YIMGA Gael <gael.yimen-yimga@sgcib.com<mailto:gael.yimen-yimga@sgcib.com>>:
Hello Dear,

I made an estimation of a number of nodes of a cluster that can be supplied by 720GB of data/day.
My estimation gave me 367 datanodes in a year. I’m a bit afraid by that amount of datanodes.
The assumptions, I used are the followings :

-          Daily supply (feed) : 720GB

-          HDFS replication factor: 3

-          Booked space for each disk outside HDFS: 30%

-          Size of a disk: 3TB.

I have two questions.

First, I would like to know if my assumptions are well taken?
Secondly, could someone help me to evaluate that cluster, to let me be sure that my results
are not to excessive, please ?

Standing by for your feedback

Warm regard

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