Query over efficient utilization of cluster using fair scheduling

[Pallavi Palleti]

Hi all,

I am experimenting with fair scheduler in a cluster of 10 machines. The 
users are given default values("0") for minMaps and minReduces in fair 
scheduler parameters. When I tried to run two jobs using the same 
username, the fair scheduler is giving 100% fair share to first 
job(needs 2 mappers) and the second job(needs10 mappers) is in waiting 
mode though the cluster is totally idle. Allowing these jobs to run 
simultaneously would take only 10% of total available mappers. However, 
the second job is not allowed to run till the first job is over. It 
would be great if some one can suggest some parameter tuning which can 
allow efficient utilization of cluster. Efficient I mean, allowing jobs 
to run when the cluster is idle rather letting them in waiting mode. I 
am not sure whether setting "minMaps, minReduces" for each user would 
resolve the issue. Kindly clarify.

Thanks
Pallavi