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https://issues.apache.org/jira/browse/HDFS-5526?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13827227#comment-13827227
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Vinay commented on HDFS-5526:
-----------------------------
bq. For example, the ctime or some ids may have been changed in some unexpected
way without being noticed
Overwriting the version file in datanode current directory is only during
format and upgrade.
But during upgrade only clusterId and layoutVersion are overwritten, ctime is
never modified. clusterId and layoutVersion are never going to change
dynamically. right?
{noformat} if (LayoutVersion.supports(Feature.FEDERATION, layoutVersion)) {
clusterID = nsInfo.getClusterID();
layoutVersion = nsInfo.getLayoutVersion();
writeProperties(sd);
return;
}{noformat}
Hi [~kihwal], Patch looks really simple. +1
do you think we need to update this comment now..?
{code} * Do nothing, if previous directory does not exist.{code}
> Datanode cannot roll back to previous layout version
> ----------------------------------------------------
>
> Key: HDFS-5526
> URL: https://issues.apache.org/jira/browse/HDFS-5526
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode
> Reporter: Tsz Wo (Nicholas), SZE
> Assignee: Kihwal Lee
> Priority: Blocker
> Attachments: HDFS-5526.patch
>
>
> Current trunk layout version is -48.
> Hadoop v2.2.0 layout version is -47.
> If a cluster is upgraded from v2.2.0 (-47) to trunk (-48), the datanodes
> cannot start with -rollback. It will fail with IncorrectVersionException.
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