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https://issues.apache.org/jira/browse/HDFS-13079?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mukul Kumar Singh updated HDFS-13079:
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Description:
In some cases it necessary to rollback the Namenode back to a certain
transaction id. This is especially needed when the user issues a {{rm -Rf
-skipTrash}} by mistake.
Rolling back to a transaction id helps in taking a peek at the filesystem at a
particular instant. This jira proposes to provide a configuration variable
using which the namenode can be started upto a certain transaction id. The
filesystem will be in a readonly safemode which cannot be overridden manually.
It will only be overridden by removing the config value from the config file.
Please also note that this will not cause any changes in the filesystem state,
the filesystem will be in safemode state and no changes to the filesystem state
will be allowed.
Please note that in case a checkpoint has already happened and the requested
transaction id has been subsumed in an FSImage, then the namenode will be
started with the next nearest transaction id. Further FSImage files and edits
will be ignored.
If the checkpoint hasn't happen then the namenode will be started with the
exact transaction id.
was:
While working on some customer cases it necessary to rollback the Namenode back
to a certain transaction id. This is especially needed when the user issues a
{{rm -Rf -skipTrash}}.
Rolling back to a transaction id helps in taking a peek at the filesystem at a
particular instant. This jira proposes to provide a configuration variable
using which the namenode can be started upto a certain transaction id. The
filesystem will be in a readonly safemode which cannot be overridden manually.
It will only be overridden by removing the config value from the config file.
Please also note that this will not cause any changes in the filesystem state,
the filesystem will be in safemode state and no changes to the filesystem state
will be allowed.
Please note that in case a checkpoint has already happened and the requested
transaction id has been subsumed in an FSImage, then the namenode will be
started with the next nearest transaction id. Further FSImage files and edits
will be ignored.
If the checkpoint hasn't happen then the namenode will be started with the
exact transaction id.
> Provide a config to start namenode in safemode state upto a certain
> transaction id
> ----------------------------------------------------------------------------------
>
> Key: HDFS-13079
> URL: https://issues.apache.org/jira/browse/HDFS-13079
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Mukul Kumar Singh
> Assignee: Mukul Kumar Singh
> Priority: Major
> Attachments: HDFS-13079.001.patch
>
>
> In some cases it necessary to rollback the Namenode back to a certain
> transaction id. This is especially needed when the user issues a {{rm -Rf
> -skipTrash}} by mistake.
> Rolling back to a transaction id helps in taking a peek at the filesystem at
> a particular instant. This jira proposes to provide a configuration variable
> using which the namenode can be started upto a certain transaction id. The
> filesystem will be in a readonly safemode which cannot be overridden
> manually. It will only be overridden by removing the config value from the
> config file. Please also note that this will not cause any changes in the
> filesystem state, the filesystem will be in safemode state and no changes to
> the filesystem state will be allowed.
> Please note that in case a checkpoint has already happened and the requested
> transaction id has been subsumed in an FSImage, then the namenode will be
> started with the next nearest transaction id. Further FSImage files and edits
> will be ignored.
> If the checkpoint hasn't happen then the namenode will be started with the
> exact transaction id.
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