On Thu, May 7, 2009 at 6:05 AM, Foss User wrote:
> Thanks for your response again. I could not understand a few things in
> your reply. So, I want to clarify them. Please find my questions
> inline.
>
> On Thu, May 7, 2009 at 2:28 AM, Todd Lipcon wrote:
>> On Wed, May 6, 2009 at 1:46 PM, Foss Use
Thanks for your response again. I could not understand a few things in
your reply. So, I want to clarify them. Please find my questions
inline.
On Thu, May 7, 2009 at 2:28 AM, Todd Lipcon wrote:
> On Wed, May 6, 2009 at 1:46 PM, Foss User wrote:
>> 2. Is the meta data for file blocks on data nod
On Wed, May 6, 2009 at 1:46 PM, Foss User wrote:
> Thanks for your response. I got a few more questions regarding
> optimizations.
>
> 1. Does hadoop clients locally cache the data it last requested?
>
I don't know the DFS read path very well, but I don't believe there is any
built in cache here
Thanks for your response. I got a few more questions regarding optimizations.
1. Does hadoop clients locally cache the data it last requested?
2. Is the meta data for file blocks on data node kept in the
underlying OS's file system on namenode or is it kept in RAM of the
name node?
3. If no mapp
On Wed, May 6, 2009 at 12:22 PM, Foss User wrote:
> 1. Do the reducers of a job start only after all mappers have finished?
>
The reducer tasks start so they can begin copying map output, but your
actual reduce function does not. This is because it doesn't know that the
data for any given key h
1. Do the reducers of a job start only after all mappers have finished?
2. Say there are 10 slave nodes. Let us say one of the nodes is very
slow as compared to other nodes. So, while the mappers in the other 9
have finished in 2 minutes, the one on the slow one might take 20
minutes. Is Hadoop i
