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https://issues.apache.org/jira/browse/HDFS-4685?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13852294#comment-13852294
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Chris Nauroth commented on HDFS-4685:
-------------------------------------
I can loop back now on the question of using inode features vs. the custom data
structure I described in the design doc.
The patch in HDFS-5658 implements the feature approach. Development on this
has come together much more quickly than the custom approach that I was
starting in HDFS-5595. In the final analysis, the custom approach is more
compact than the feature approach, at least for the first 64511 distinct ACLs
in a namesystem, which can be referenced via reuse of unused space in the
permission bits. Beyond that number, the savings vanish, because we need to
start involving the INode ACL Map as an external data structure with per-inode
pointer overhead. The custom approach requires much more complex code compared
to the feature approach.
At this point, the plan is to go with the feature approach. Most importantly,
the feature approach still has the characteristic that people who don't use
ACLs at all won't take any extra per-inode memory hit in their deployments. We
can keep the design doc for the custom approach here as a back-pocket idea if
we find we really need it, but at this point it would likely be premature
optimization.
In the next revision of the design doc, I'll make the changes to state that
this is implemented as an inode feature.
> Implementation of ACLs in HDFS
> ------------------------------
>
> Key: HDFS-4685
> URL: https://issues.apache.org/jira/browse/HDFS-4685
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: hdfs-client, namenode, security
> Affects Versions: 1.1.2
> Reporter: Sachin Jose
> Assignee: Chris Nauroth
> Attachments: HDFS-ACLs-Design-1.pdf
>
>
> Currenly hdfs doesn't support Extended file ACL. In unix extended ACL can be
> achieved using getfacl and setfacl utilities. Is there anybody working on
> this feature ?
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