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MapReduce, mail # user - Re: disk used percentage is not symmetric on datanodes (balancer)


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Re: disk used percentage is not symmetric on datanodes (balancer)
Bertrand Dechoux 2013-03-18, 21:43
Hi,

It is not explicitly said but did you use the balancer?
http://hadoop.apache.org/docs/r1.0.4/commands_manual.html#balancer

Regards

Bertrand

On Mon, Mar 18, 2013 at 10:01 PM, Tapas Sarangi <[EMAIL PROTECTED]>wrote:

> Hello,
>
> I am using one of the old legacy version (0.20) of hadoop for our cluster.
> We have scheduled for an upgrade to the newer version within a couple of
> months, but I would like to understand a couple of things before moving
> towards the upgrade plan.
>
> We have about 200 datanodes and some of them have larger storage than
> others. The storage for the datanodes varies between 12 TB to 72 TB.
>
> We found that the disk-used percentage is not symmetric through all the
> datanodes. For larger storage nodes the percentage of disk-space used is
> much lower than that of other nodes with smaller storage space. In larger
> storage nodes the percentage of used disk space varies, but on average
> about 30-50%. For the smaller storage nodes this number is as high as
> 99.9%. Is this expected ? If so, then we are not using a lot of the disk
> space effectively. Is this solved in a future release ?
>
> If no, I would like to know  if there are any checks/debugs that one can
> do to find an improvement with the current version or upgrading hadoop
> should solve this problem.
>
> I am happy to provide additional information if needed.
>
> Thanks for any help.
>
> -Tapas
>
>