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https://issues.apache.org/jira/browse/ZOOKEEPER-2003?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14086179#comment-14086179
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Liang Xie commented on ZOOKEEPER-2003:
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Seems there's no JAVA api could do this, one possible solution is JNI.
ps: It's still safe if using XFS:) but really need a directory fsync w/ ext4,
in theory.
[~fpj], i think you missed Samer's point...
> Missing fsync() on the logs parent directory
> --------------------------------------------
>
> Key: ZOOKEEPER-2003
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2003
> Project: ZooKeeper
> Issue Type: Bug
> Affects Versions: 3.4.6
> Reporter: Samer Al-Kiswany
>
> After studying the steps ZooKeeper takes to update the logs we found the
> following bug. The bug may not manifest in the current file system
> implementations, but it violates the POSIX recommendations and may be an
> issue in some file systems.
> Looking at the strace of zookeeper we see the following:
> mkdir(v)
> create(v/log)
> append(v/log)
> trunk(v/log)
> write(v/log)
> fdatasync(v/log)
> Although the data is fdatasynced to the log, the parent directory was never
> fsynced, consequently in case of a crash, the parent directory or the log
> file may be lost, as the parent directory and file metadata were never
> persisted on disk.
> To be safe, both the log directory, and parent directory of the log directory
> should be fsynced as well.
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