DistCP is a full blown mapreduce job (mapper only, where the mappers do a
"fully" parallel copy to the detsination).
CP appears (correct me if im wrong) to simply invoke the FileSystem and
issues a copy command for every source file.
I have an additional question: how is CP which is internal to a cluster
optimized (if at all) ?
On Wed, Apr 10, 2013 at 7:28 PM, 麦树荣 <[EMAIL PROTECTED]> wrote:
> I think it' better using Copy in the same cluster while using distCP
> between clusters, and cp command is a hadoop internal parallel process and
> will not copy files locally.
> *From:* KayVajj <[EMAIL PROTECTED]>
> *Date:* 2013-04-11 06:20
> *To:* [EMAIL PROTECTED]
> *Subject:* Copy Vs DistCP
> I have few questions regarding the usage of DistCP for copying
> files in the same cluster.
> 1) Which one is better within a same cluster and what factors (like file
> size etc) wouldinfluence the usage of one over te other?
> 2) when we run a cp command like below from a client node of the cluster
> (not a data node), How does the cp command work
> i) like an MR job
> ii) copy files locally and then it copy it back at the new location.
> Example of the copy command
> hdfs dfs -cp /<some_location>/file /<new_location>/
> Thanks, your responses are appreciated.
> -- Kay