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https://issues.apache.org/jira/browse/HDFS-6000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13911412#comment-13911412
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Tsz Wo (Nicholas), SZE commented on HDFS-6000:
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- I think it is good to keep the txid parameter in
FSImage.hasRollbackFSImage(). How about we store it in rollingUpgradeInfo? We
don't need to add any code for persisting it since it is already in the file
name.
- In FSNamesystem.startRollingUpgrade(), we cannot require NN to be in safemode
for non-HA case since it is a write operation. Let's just
checkNameNodeSafeMode for both HA and non-HA cases. It was my mistake actually.
- For non-HA case, we should checkRollingUpgrade and getFSImage().checkUpgrade
before saving rollback image. We also need to set createdRollbackImages to
true after saved rollback image.
- For HA case, do we need to roll edit before logStartRollingUpgrade? Do we
still want the StartRollingUpgrade transaction to be the first transaction in a
edit log segment?
- FSNamesystem.stopRollingUpgrade is only used once. How about remove it?
> Avoid saving namespace when starting rolling upgrade
> ----------------------------------------------------
>
> Key: HDFS-6000
> URL: https://issues.apache.org/jira/browse/HDFS-6000
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode, ha, hdfs-client, namenode
> Reporter: Jing Zhao
> Assignee: Jing Zhao
> Attachments: HDFS-6000.000.patch, HDFS-6000.001.patch,
> HDFS-6000.002.patch
>
>
> Currently when administrator sends the "rollingUpgrade start" command to the
> active NN, the NN will trigger a checkpoint (the rollback fsimage). This will
> cause NN not able to serve for a period of time.
> An alternative way is just to let the SBN do checkpoint, and rename the first
> checkpoint after starting the rolling upgrade to rollback image. After the
> rollback image is on both the ANN and the SBN, administrator can start
> upgrading the software.
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