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parallel cat
I have many large files ranging from 2gb to 800gb and I use hadoop fs -cat a
lot to pipe to various programs.

I was wondering if its possible to prefetch the data for clients with more
bandwidth. Most of my clients have 10g interface and datanodes are 1g.

I was thinking, prefetch x blocks (even though it will cost extra memory)
while reading block y. After block y is read, read the prefetched blocked
and then throw it away.

It should be used like this:
export PREFETCH_BLOCKS=2 #default would be 1
hadoop fs -pcat hdfs://namenode/verylarge file | program

Any thoughts?

--- Get your facts first, then you can distort them as you please.--
Steve Loughran 2011-07-06, 11:35
Rita 2011-07-07, 07:22
Steve Loughran 2011-07-07, 09:35
Rita 2011-07-07, 12:36