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https://issues.apache.org/jira/browse/HADOOP-16085?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16765489#comment-16765489
 ] 

Ben Roling commented on HADOOP-16085:
-------------------------------------

I commented on HADOOP-15625:

https://issues.apache.org/jira/browse/HADOOP-15625?focusedCommentId=16765486&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-16765486

 

As mentioned there, I have a patch for that issue.  I'm having trouble 
uploading it for some reason though.  It is as though I don't have permission.  
The attachment area of the Jira doesn't look like it does on this issue where I 
AM allowed to upload.

In that patch I elected to just use a vanilla IOException for the exception 
type.  Alternative suggestions are welcome.

> S3Guard: use object version to protect against inconsistent read after 
> replace/overwrite
> ----------------------------------------------------------------------------------------
>
>                 Key: HADOOP-16085
>                 URL: https://issues.apache.org/jira/browse/HADOOP-16085
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/s3
>    Affects Versions: 3.2.0
>            Reporter: Ben Roling
>            Priority: Major
>         Attachments: HADOOP-16085_002.patch, HADOOP-16085_3.2.0_001.patch
>
>
> Currently S3Guard doesn't track S3 object versions.  If a file is written in 
> S3A with S3Guard and then subsequently overwritten, there is no protection 
> against the next reader seeing the old version of the file instead of the new 
> one.
> It seems like the S3Guard metadata could track the S3 object version.  When a 
> file is created or updated, the object version could be written to the 
> S3Guard metadata.  When a file is read, the read out of S3 could be performed 
> by object version, ensuring the correct version is retrieved.
> I don't have a lot of direct experience with this yet, but this is my 
> impression from looking through the code.  My organization is looking to 
> shift some datasets stored in HDFS over to S3 and is concerned about this 
> potential issue as there are some cases in our codebase that would do an 
> overwrite.
> I imagine this idea may have been considered before but I couldn't quite 
> track down any JIRAs discussing it.  If there is one, feel free to close this 
> with a reference to it.
> Am I understanding things correctly?  Is this idea feasible?  Any feedback 
> that could be provided would be appreciated.  We may consider crafting a 
> patch.



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