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https://issues.apache.org/jira/browse/HDFS-1380?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thanh Do updated HDFS-1380:
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    Description: 
1. Say we have 2 racks: rack-0 and rack-1. 
Rack-0 has dn1, dn2, dn3. Rack-0 has dn4, dn5, dn6.
 
2. Suppose client is in rack-0, and the write pipeline is:
client --> localnode --> other rack --> other rack
In this example we have the pipeline client-dn1-dn4-dn6.
That is rack0-rack0-rack1-rack1. So far so good.
 
3. Now other client comes, and append to file.
This client is also in rack-0. Interestingly,
the append pipeline is client-dn6-dn4-dn1.
That is the new client (from rack0) sends packet 
to the first node in pipeline (dn6) which belongs to rack1.

This bug was found by our Failure Testing Service framework:
http://www.eecs.berkeley.edu/Pubs/TechRpts/2010/EECS-2010-98.html
For questions, please email us: Thanh Do (than...@cs.wisc.edu) and 
Haryadi Gunawi (hary...@eecs.berkeley.edu)

  was:
1. Say we have 2 racks: rack-0 and rack-1. 
Rack-0 has dn1, dn2, dn3. Rack-0 has dn4, dn5, dn6.
 
2. Suppose client is in rack-0, and the write pipeline is:
client --> localnode --> other rack --> other rack
In this example we have the pipeline client-dn1-dn4-dn6.
That is rack0-rack0-rack1-rack1. So far so good.
 
3. Now other client comes, and append to file.
This client is also in rack-0. Interestingly,
the append pipeline is client-dn6-dn4-dn1.
That is the new client (from rack0) sends packet 
to the first node in pipeline (dn6) which belongs to rack1.


> The append pipeline does not followed TSP principal
> ---------------------------------------------------
>
>                 Key: HDFS-1380
>                 URL: https://issues.apache.org/jira/browse/HDFS-1380
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: hdfs client
>    Affects Versions: 0.20-append
>            Reporter: Thanh Do
>
> 1. Say we have 2 racks: rack-0 and rack-1. 
> Rack-0 has dn1, dn2, dn3. Rack-0 has dn4, dn5, dn6.
>  
> 2. Suppose client is in rack-0, and the write pipeline is:
> client --> localnode --> other rack --> other rack
> In this example we have the pipeline client-dn1-dn4-dn6.
> That is rack0-rack0-rack1-rack1. So far so good.
>  
> 3. Now other client comes, and append to file.
> This client is also in rack-0. Interestingly,
> the append pipeline is client-dn6-dn4-dn1.
> That is the new client (from rack0) sends packet 
> to the first node in pipeline (dn6) which belongs to rack1.
> This bug was found by our Failure Testing Service framework:
> http://www.eecs.berkeley.edu/Pubs/TechRpts/2010/EECS-2010-98.html
> For questions, please email us: Thanh Do (than...@cs.wisc.edu) and 
> Haryadi Gunawi (hary...@eecs.berkeley.edu)

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