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From Doug Cutting <cutt...@apache.org>
Subject Re: Large data sets
Date Tue, 06 Feb 2007 20:01:39 GMT
Konstantin Shvachko wrote:
> 200 bytes per file is theoretically correct, but rather optimistic :-(
>  From a real system memory utilization I can see that HDFS uses 1.5-2K 
> per file.
> And since each real file is internally represented by two files (1 real 
> + 1 crc) the real
> estimate per file should read 3-4K.

But also note that there are plans to address these over the coming 
months.  For a start:


Once checksums are optional then we can replace their implementation in 
HDFS with something that does not consume namespace.

Long term we hope to approach ~100 bytes per file.


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