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https://issues.apache.org/jira/browse/HDFS-3510?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Colin Patrick McCabe updated HDFS-3510:
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Attachment: HDFS-3510.001.patch
Here's a patch for trunk.
> Fix FSEditLog pre-allocation
> ----------------------------
>
> Key: HDFS-3510
> URL: https://issues.apache.org/jira/browse/HDFS-3510
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 1.0.0, 2.0.0-alpha
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Fix For: 1.0.0, 2.0.1-alpha
>
> Attachments: HDFS-3510-b1.001.patch, HDFS-3510-b1.002.patch,
> HDFS-3510.001.patch
>
>
> In the FSEditLog, we want to avoid running out of space in the middle of
> writing an edit log operation to the disk. We do this by a process called
> "preallocation"-- reserving space on the disk for the upcoming edit log
> entries before beginning to write them.
> There are two problems:
> In both trunk and branch-1:
> * We only try to do preallocation when the current position is less than 4096
> bytes from the end of the file. However, bufReady starts out at 512kb, and
> only gets bigger from there. There is no way that 4kb is enough space to
> reserve.
> Only in branch-1:
> * The branch-1 code unfortunately creates sparse files rather than actually
> pre-allocating the required space.
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