So under Apache Hadoop, how do you specify the location of when and where a directory will be created on HDFS? 

As an example, if I want to create a /coldData directory in HDFS as a place to store my older data sets, How does that get assigned specifically to a RAIDed HDFS?
(Or even specific machines?) 

I know I can do this in MapR's distribution, but I am not aware of this feature being made available in the Apache based releases? 

Is this part of the latest feature set? 



On Aug 8, 2012, at 12:31 PM, Steve Loughran <stevel@hortonworks.com> wrote:

On 8 August 2012 09:46, Sourygna Luangsay <sluangsay@pragsis.com> wrote:

Hi folks!

One of the scenario I can think in order to take advantage of HDFS RAID without suffering this penalty is:

-          Using normal HDFS with default replication=3 for my “fresh data”

-          Using HDFS RAID for my historical data (that is barely used by M/R)


exactly: less space use on cold data, with the penalty that access performance can be worse. As the majority of data on a hadoop cluster is usually "cold", it's a space and power efficient story for the archive data

Steve Loughran
Hortonworks Inc