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From "Konstantin Shvachko (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-8468) Umbrella of enhancements to support different failure and locality topologies
Date Fri, 23 Nov 2012 07:32:59 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-8468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13503097#comment-13503097
] 

Konstantin Shvachko commented on HADOOP-8468:
---------------------------------------------

Junping,
Checked your article with performance results. Got a question about it. 
How do you explain the performance gain with DFSIO?
MapReduce-wise DFSIO is completely unaware of the locality of the data it reads, because input
data is just the file with the file name that the mapper should read. So the input file with
name of the file to read is local to task, but not the file that it then reads.
Not saying there is anything wrong with your results, I just think it needs more explanation.
                
> Umbrella of enhancements to support different failure and locality topologies
> -----------------------------------------------------------------------------
>
>                 Key: HADOOP-8468
>                 URL: https://issues.apache.org/jira/browse/HADOOP-8468
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: ha, io
>    Affects Versions: 1.0.0, 2.0.0-alpha
>            Reporter: Junping Du
>            Assignee: Junping Du
>         Attachments: HADOOP-8468-total.patch, HADOOP-8468-total-v3.patch, HVE_Hadoop
World Meetup 2012.pptx, HVE User Guide on branch-1(draft ).pdf, Proposal for enchanced failure
and locality topologies.pdf, Proposal for enchanced failure and locality topologies (revised-1.0).pdf
>
>
> The current hadoop network topology (described in some previous issues like: Hadoop-692)
works well in classic three-tiers network when it comes out. However, it does not take into
account other failure models or changes in the infrastructure that can affect network bandwidth
efficiency like: virtualization. 
> Virtualized platform has following genes that shouldn't been ignored by hadoop topology
in scheduling tasks, placing replica, do balancing or fetching block for reading: 
> 1. VMs on the same physical host are affected by the same hardware failure. In order
to match the reliability of a physical deployment, replication of data across two virtual
machines on the same host should be avoided.
> 2. The network between VMs on the same physical host has higher throughput and lower
latency and does not consume any physical switch bandwidth.
> Thus, we propose to make hadoop network topology extend-able and introduce a new level
in the hierarchical topology, a node group level, which maps well onto an infrastructure that
is based on a virtualized environment.

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