[
https://issues.apache.org/jira/browse/HADOOP-1869?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12628073#action_12628073
]
rangadi edited comment on HADOOP-1869 at 9/3/08 10:55 AM:
---------------------------------------------------------------
> a file create (such as expansion of an archive and a distcp), [...]
During create is not enough even for these use cases. Say distcp copies 10GB
file and sets Mod time at create time (to t - 1month), and the last block is
written 1 min later.. then the mod time after Distcp will be (t + 1min) rather
than (t - 1month). -1 for extra options to create, or close, etc.
Why not just provide utimes().. since we are using POSIX as a tie breaker?
Another Konstantin's point is that FS should not allow setting future time..
which sounds ok.. but it is just a file attribute to help users not something
filesystem inherently depends upon. I don't see need to police it that much ..
and since POSIX is a tie breaker we could just stick to it functionality. Note
that all the use cases we need to be able to set modtime too.
was (Author: rangadi):
> a file create (such as expansion of an archive and a distcp), [...]
During create is not enough even for these test cases. Say distcp copies 10GB
file and set Mod time at create time (to t - 1month), and the last block was
written 1 min later.. then the mod time after Distcp will be (t + 1min) rather
than (t - 1month). -1 for extra options to create, or close, etc.
Why not just provide utimes().. since we are using POSIX as a tie breaker?
Another Konstantin's point is that FS should not allow setting future time..
which sounds ok.. but it is just a file attribute to help users not something
filesystem inherently depends upon. I don't see need to police it that much ..
and since POSIX is a tie breaker we could just stick to it. For all the use
case we need to be able to set modtime too.
> access times of HDFS files
> --------------------------
>
> Key: HADOOP-1869
> URL: https://issues.apache.org/jira/browse/HADOOP-1869
> Project: Hadoop Core
> Issue Type: New Feature
> Components: dfs
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Fix For: 0.19.0
>
> Attachments: accessTime1.patch, accessTime4.patch, accessTime5.patch
>
>
> HDFS should support some type of statistics that allows an administrator to
> determine when a file was last accessed.
> Since HDFS does not have quotas yet, it is likely that users keep on
> accumulating files in their home directories without much regard to the
> amount of space they are occupying. This causes memory-related problems with
> the namenode.
> Access times are costly to maintain. AFS does not maintain access times. I
> thind DCE-DFS does maintain access times with a coarse granularity.
> One proposal for HDFS would be to implement something like an "access bit".
> 1. This access-bit is set when a file is accessed. If the access bit is
> already set, then this call does not result in a transaction.
> 2. A FileSystem.clearAccessBits() indicates that the access bits of all files
> need to be cleared.
> An administrator can effectively use the above mechanism (maybe a daily cron
> job) to determine files that are recently used.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
