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From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-3886) Shutdown requests can possibly check for checkpoint issues (corrupted edits) and save a good namespace copy before closing down?
Date Sat, 01 Sep 2012 11:55:08 GMT

    [ https://issues.apache.org/jira/browse/HDFS-3886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13446653#comment-13446653
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Steve Loughran commented on HDFS-3886:
--------------------------------------

currently a kill -2 is the event sent from init.d to trigger a managed shutdown, but it needs
to complete within a bounded period, otherwise robust init.d/ linux HA scripts will escalate
to a -9; this is because they need to reliably shut down the system.

Any change that reverts service scripts from having timeout+escalation would be counterproductive
from a service management perspective.

Now, if there were another signal handler that triggered lock up and system save, that could
be good -but that would lie outside init.d land
                
> Shutdown requests can possibly check for checkpoint issues (corrupted edits) and save
a good namespace copy before closing down?
> --------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-3886
>                 URL: https://issues.apache.org/jira/browse/HDFS-3886
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>    Affects Versions: 2.0.0-alpha
>            Reporter: Harsh J
>            Priority: Minor
>
> HDFS-3878 sorta gives me this idea. Aside of having a method to download it to a different
location, we can also lock up the namesystem (or deactivate the client rpc server) and save
the namesystem before we complete up the shutdown.
> The init.d/shutdown scripts would have to work with this somehow though, to not kill
-9 it when in-process. Also, the new image may be stored in a shutdown.chkpt directory, to
not interfere in the regular dirs, but still allow easier recovery.
> Obviously this will still not work if all directories are broken. So maybe we could have
some configs to tackle that as well?
> I haven't thought this through, so let me know what part is wrong to do :)

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