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From "Raghu Angadi (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-3677) Problems with generation stamp upgrade
Date Thu, 10 Jul 2008 01:27:31 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-3677?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12612340#action_12612340

Raghu Angadi commented on HADOOP-3677:

I think it is better to fix the problem than asking users to go through different procedure
for upgrade. There are users with vastly different expertise and caution. What happens if
they don't follow the procedure by mistake?

Also this special work around needs to be followed in even in future when some one is upgrading
from 0.17 to 0.20.

> Problems with generation stamp upgrade
> --------------------------------------
>                 Key: HADOOP-3677
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3677
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.18.0
>            Reporter: Konstantin Shvachko
>            Assignee: dhruba borthakur
>            Priority: Blocker
>             Fix For: 0.18.0
> # The generation stamp upgrade renames blocks' meta-files so that the name contains the
block generation stamp as stated in HADOOP-2656.
> If a data-node has blocks that do not belong to any files and the name-node asks the
data-node to remove those blocks 
> during or before the upgrade started the data-node will remove the blocks but not the
meta-files because their names 
> are still in the old format which is not recognized by the new code. So we can end up
with a number of garbage files which
> will be hard to recognize that they are unused and the system will never remove them
> I think this should be handled by the upgrade code in the end, but may be it will be
right to fix HADOOP-3002 for the 0.18 release,
> which will avoid scheduling block removal when the name-node is in safe-mode.
> # I was not able to get the upgrade -force option to work. This option lets the name-node
proceed with a distributed upgrade even if
> the data-nodes are not able to complete their local upgrades. Did we test this feature
at all for the generation stamp upgrade?

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