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https://issues.apache.org/jira/browse/HDFS-2736?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13177791#comment-13177791
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Todd Lipcon commented on HDFS-2736:
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bq. if we fail over to the SBN does it continue to checkpoint?
If the only active NN comes back, it will start in standby mode and then do
checkpoints against the other one. It's only if the former active remains dead
for some time that we might have a problem.
bq. If not the log grows unbounded until the old primary comes back, if so does
that create performance problems since the primary wasn't previously
checkpointing?
Certainly the first startup after a long outage will be slower, since it has to
replay a lot of transactions. But it's not any different than what happens
today if the 2NN goes down for some length of time.
Given that people currently run successfully with only a single 2NN, I don't
think this is particularly high priority. Do you disagree?
> HA: support separate SBN and 2NN?
> ---------------------------------
>
> Key: HDFS-2736
> URL: https://issues.apache.org/jira/browse/HDFS-2736
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ha
> Affects Versions: HA branch (HDFS-1623)
> Reporter: Eli Collins
>
> HDFS-2291 adds support for making the SBN capable of checkpointing, seems
> like we may also need to support the 2NN checkpointing as well. Eg if we fail
> over to the SBN does it continue to checkpoint? If not the log grows
> unbounded until the old primary comes back, if so does that create
> performance problems since the primary wasn't previously checkpointing?
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