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Date: Tue, 3 Feb 2015 00:25:35 +0000 (UTC)
From: "Jing Zhao (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12726376.1404927572000.236025.1422923135590@Atlassian.JIRA>
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Subject: [jira] [Commented] (HDFS-6651) Deletion failure can leak inodes
 permanently.
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    [ https://issues.apache.org/jira/browse/HDFS-6651?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14302540#comment-14302540 ] 

Jing Zhao commented on HDFS-6651:
---------------------------------

The current patch takes the #5 solution. This simplifies the quota calculation and avoids the inode leaking while deletion. Since the current snapshot solution takes COW semantic, the diffs may not contribute a lot to the NS quota usage and NN memory usage. Thus I think the incompatibility here may not be an issue.

> Deletion failure can leak inodes permanently.
> ---------------------------------------------
>
>                 Key: HDFS-6651
>                 URL: https://issues.apache.org/jira/browse/HDFS-6651
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Kihwal Lee
>            Assignee: Jing Zhao
>            Priority: Critical
>         Attachments: HDFS-6651.000.patch, HDFS-6651.001.patch, HDFS-6651.002.patch
>
>
> As discussed in HDFS-6618, if a deletion of tree fails in the middle, any collected inodes and blocks will not be removed from {{INodeMap}} and {{BlocksMap}}. 
> Since fsimage is saved by iterating over {{INodeMap}}, the leak will persist across name node restart. Although blanked out inodes will not have reference to blocks, blocks will still refer to the inode as {{BlockCollection}}. As long as it is not null, blocks will live on. The leaked blocks from blanked out inodes will go away after restart.
> Options (when delete fails in the middle)
> - Complete the partial delete: edit log the partial delete and remove inodes and blocks. 
> - Somehow undo the partial delete.
> - Check quota for snapshot diff beforehand for the whole subtree.
> - Ignore quota check during delete even if snapshot is present.


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