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https://issues.apache.org/jira/browse/HDFS-1801?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13030395#comment-13030395
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Eli Collins commented on HDFS-1801:
-----------------------------------
IIUC the sequence in your comment above only applies when the edits dir lives
on a different volume from the image dir.
Comments/questions:
* Doesn't the last test in TestNameEditsConfigs#testNameEditsConfigsFailure
need an fail("...") before the catch since we expect this last test to fail? Ie
if it does not fail the test can still pass.
* Header comment of readTransactionIdFile still refers to time
* Useful to have a comment by NameNodeFile.TIME indicating this is pre-HDFS-1073
* Would CKPT_TXID be a more descriptive name than SEEN_TXID since this is the
txid at the time of checkpoint?
* The removed edit log ops codes need to be reintroduced in the future to fix
the BN right? In which case perhaps leave them in for now.
Patch looks good.
> Remove use of timestamps to identify checkpoints and logs
> ---------------------------------------------------------
>
> Key: HDFS-1801
> URL: https://issues.apache.org/jira/browse/HDFS-1801
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: name-node
> Affects Versions: Edit log branch (HDFS-1073)
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Fix For: Edit log branch (HDFS-1073)
>
> Attachments: hdfs-1801.txt, hdfs-1801.txt, hdfs-1801.txt,
> hdfs-1801.txt
>
>
> Currently, the NameNode validates checkpoint uploads by using timestamps
> associated with checkpoints and edit logs. However, now that we have
> transaction IDs that uniquely identify each point in time in the history of a
> namespace, it is more robust to simply use transaction IDs to identify images
> and edits.
> This JIRA is to remove the use of editsTime and checkpointTime and replace it
> with:
> * {{lastCheckpointTxId}} - the highest transaction ID reflected in the most
> recently saved fsimage file
> * {{lastLogRollTxId}} - the highest transaction ID in {{edits}} when
> {{rollFsImage}} was called by the checkpointing node.
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