[jira] [Updated] (FLUME-1516) FileChannel Write Dual Checkpoints to avoid replays

["Brock Noland (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLUME-1516?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Brock Noland updated FLUME-1516:
--------------------------------

    Component/s: File Channel
        Summary: FileChannel Write Dual Checkpoints to avoid replays  (was: Write Dual Checkpoints to avoid replays)
    
> FileChannel Write Dual Checkpoints to avoid replays
> ---------------------------------------------------
>
>                 Key: FLUME-1516
>                 URL: https://issues.apache.org/jira/browse/FLUME-1516
>             Project: Flume
>          Issue Type: New Feature
>          Components: Channel, File Channel
>    Affects Versions: v1.3.0
>            Reporter: Brock Noland
>            Assignee: Hari Shreedharan
>             Fix For: v1.4.0
>
>         Attachments: DualCheckpoints.pdf, DualCheckpointsv2.pdf, DualCheckpointsv3.pdf, FLUME-1516-1.patch, FLUME-1516-2.patch, FLUME-1516-3.patch, FLUME-1516-4.patch, FLUME-1516-5.patch, FLUME-1516-6.patch, FLUME-1516-7.patch, FLUME-1516.patch
>
>
> Per the LFS paper (http://www.cs.berkeley.edu/~brewer/cs262/LFS.pdf) we can write two checkpoints to avoid replaying the logs in the case we crash/shutdown while writing a checkpoint.
> Section 4:
> "In order to handle a crash during a checkpoint operation there are actually two checkpoint regions, and checkpoint operations alternate between them. The checkpoint time is in the last block of the checkpoint so if the checkpoint fails the time will not be updated. During reboot, the system reads both checkpoint regions and uses the one with the most recent time."

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