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https://issues.apache.org/jira/browse/HDFS-4462?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13568946#comment-13568946
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Aaron T. Myers commented on HDFS-4462:
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[~acmurthy] Blocker? Probably not. Pretty good to have? I think so. There's a
pretty simple work-around: when upgrading from a pre-federation version of
HDFS, blow away your 2NN checkpoint dirs before starting up your 2NN again. A
problem will arise if an admin doesn't notice that all of their 2NN checkpoints
are failing post-upgrade.
Regardless, it's a pretty simple change - I'm hoping it can get committed today.
> 2NN will fail to checkpoint after an HDFS upgrade from a pre-federation
> version of HDFS
> ---------------------------------------------------------------------------------------
>
> Key: HDFS-4462
> URL: https://issues.apache.org/jira/browse/HDFS-4462
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.0.2-alpha
> Reporter: Aaron T. Myers
> Assignee: Aaron T. Myers
> Attachments: HDFS-4462.patch, HDFS-4462.patch
>
>
> The 2NN currently has logic to detect when its on-disk FS metadata needs an
> upgrade with respect to the NN's metadata (i.e. the layout versions are
> different) and in this case it will proceed with the checkpoint despite
> storage signatures not matching precisely if the BP ID and Cluster ID do
> match exactly. However, in situations where we're upgrading from versions of
> HDFS prior to federation, which had no BP IDs or Cluster IDs, checkpoints
> will always fail with an error like the following:
> {noformat}
> 13/01/31 17:02:25 ERROR namenode.SecondaryNameNode: checkpoint: Inconsistent
> checkpoint fields.
> LV = -40 namespaceID = 403832480 cTime = 1359680537192 ; clusterId =
> CID-0df6ff22-1165-4c7d-9630-429972a7737c ; blockpoolId =
> BP-1520616013-172.21.3.106-1359680537136.
> Expecting respectively: -19; 403832480; 0; ; .
> {noformat}
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