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From "Yongjun Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5749) Access time of HDFS directories stays at 1969-12-31
Date Wed, 15 Jan 2014 20:14:19 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13872538#comment-13872538

Yongjun Zhang commented on HDFS-5749:

I found the reason that the access time stays at 1969-12-31 is that it was initialized to
"0" (which is interpretated to be 1969-12-31) and never got updated.

I researched and  found that HADOOP-1869 which introduced access time of files explicitly
stated "Directories do not have access times". And I checked that the patch for this bug set
access time of directories to "0" which remains in latest code.

Quote from HADOOP-1869:
dhruba borthakur added a comment - 22/Aug/08 07:46
This patch does the following:
1. Implements access time for files. Directories do not have access times.
2. The access times of files is precise upto an hour boundary. This means that all accesses
to a file between 2Pm and 2:59PM will have an access time of 2PM.
3. The transaction to write access time to edits is not synced. It is assumed that it will
get synced as part of other transactions.
4. There is a configuration parameter to switch off access-times. By default, it is on.
5. There is a new FileSystem API setAccessTime() to set the access time on a file.

Release Note of HADOOP-1869:
Added HDFS file access times. By default, access times will be precise to the most recent
hour boundary. A configuration parameter dfs.access.time.precision (milliseconds) is used
to control this precision. Setting a value of 0 will disable persisting access times for HDFS

I'm closing this bug.

> Access time of HDFS directories stays at 1969-12-31
> ---------------------------------------------------
>                 Key: HDFS-5749
>                 URL: https://issues.apache.org/jira/browse/HDFS-5749
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.4.0
>            Reporter: Yongjun Zhang
>            Assignee: Yongjun Zhang
> Modify FsShell so that "fs -lsr" can show access time in addition to modification time,
the access time stays at 1969-12-31. This means the access time is not set up initially. Filing
this jira to fix this issue.

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