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Posted to common-dev@hadoop.apache.org by "Wendy Chien (JIRA)" <ji...@apache.org> on 2006/09/22 20:54:24 UTC
[jira] Commented: (HADOOP-432) support undelete, snapshots, or
other mechanism to recover lost files
[ http://issues.apache.org/jira/browse/HADOOP-432?page=comments#action_12436970 ]
Wendy Chien commented on HADOOP-432:
------------------------------------
Here's the current proposal. Comments are welcome.
Two config items:
* maximum size (say 5TB). DFS tries to keep recycle bin under this size.
* minimum time (say 1 hour). Files are never removed less than this time after they're deleted.
Namenode:
* keeps track of recycle bin size
* records deletion time of each file
* occasionally wakes up, scans deleted files and removes LRU files until desired size is reached, or files are too young, whichever comes first.
notes:
* namenode keeps deleted files sorted based on deletion times, so scan for oldest file is O(1). It's the equivalent of having ls -tr * (only in namenode, not exposed externally)
* it's all automatic. No user intervention ever, no purge command.
* file removal is lazy. Options:
-namenode wakes up occasionally (once a minute?) and removes *all* the files pending deletion
-namenode wakes up frequently (once a second?) and removes a small (100?) number of files at most
* deleted files are renamed with entire path, username of deleter, and time included.
> support undelete, snapshots, or other mechanism to recover lost files
> ---------------------------------------------------------------------
>
> Key: HADOOP-432
> URL: http://issues.apache.org/jira/browse/HADOOP-432
> Project: Hadoop
> Issue Type: Improvement
> Components: dfs
> Reporter: Yoram Arnon
> Assigned To: Wendy Chien
>
> currently, once you delete a file it's gone forever.
> most file systems allow some form of recovery of deleted files.
> a simple solution would be an 'undelete' command.
> a more comprehensive solution would include snapshots, manual and automatic, with scheduling options.
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