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https://issues.apache.org/jira/browse/HDFS-13079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16471282#comment-16471282
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Hanisha Koneru commented on HDFS-13079:
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Thanks [~shashikant] for updating the patch.
{{FSImageTransactionalStorageInspector#getImagesWithTransactionId}} should
return the images with txId << user supplied txId, right.
Lets say we have three fsImages - fsImage_0012, fsImage_0025 and fsImage_0040
and we want to load uptill txId 30. The function above should return both
fsImage_0025 and fsImage_0012, and in that order.
{code}
179 ret = new LinkedList<FSImageFile>();
180 for (FSImageFile img : foundImages) {
181 if (ret.isEmpty() && txid <= img.txId) {
182 ret.add(img);
183 }
{code}
In the if condition above, if txId (30) is <= img.txId (40), that image should
not be returned.
> 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: Shashikant Banerjee
> Priority: Major
> Attachments: HDFS-13079.001.patch, HDFS-13079.002.patch,
> HDFS-13079.003.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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