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https://issues.apache.org/jira/browse/HDFS-16452?focusedWorklogId=756128&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-756128
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ASF GitHub Bot logged work on HDFS-16452:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 13/Apr/22 01:54
Start Date: 13/Apr/22 01:54
Worklog Time Spent: 10m
Work Description: hfutatzhanghb commented on PR #3976:
URL: https://github.com/apache/hadoop/pull/3976#issuecomment-1097470379
> Sorry for the delay in my response @hfutatzhanghb.
>
> I want to make sure I understand your proposal fully. I think what you are
saying is this:
>
> Currently when using `ConfiguredFailoverProxyProvider`, we have a single
config, `dfs.ha.namenodes.<nsid>`, where we list all NN addresses. Since we
don't know the state of any of the addresses, we have to scan all of them to
find the active. Instead, we could have two configs, e.g.
`dfs.ha.namenodes.<nsid>.hanodes` and `dfs.ha.namenodes.<nsid>.observers`. The
first lists NNs that could be either ACTIVE or STANDBY state. The second lists
only NNs that could be OBSERVER state. (alternatively,
`dfs.ha.namenodes.<nsid>` could remain the same and still contain all NNs, and
we could just add the additional config `dfs.ha.namenodes.<nsid>.observers` to
mark which of the list are observers, or even add a new per-NN config like
`dfs.namenode.observer-only.<nsid>.<nnid>`) It's not possible to transition NNs
in or out of OBSERVER state w/o changing the config on the client side to move
NNs between the two lists. This is okay because we assume that we have enough
NNs in the ACTIVE+STANDBY pool to meet our HA needs, and OBSERVER NNs are only
used for scaling reads, not providing HA.
>
> Do I have that right? If so, I think this is a reasonable proposal. I
believe our installations at LinkedIn also assume that ONNs don't participate
in SbNN/ANN failover transitions.
@xkrogen ，totally right， eric！ thanks for your reply. I will submit the
patch soon. thanks!
Issue Time Tracking
-------------------
Worklog Id: (was: 756128)
Time Spent: 3h 20m (was: 3h 10m)
> msync RPC should send to Acitve Namenode directly
> --------------------------------------------------
>
> Key: HDFS-16452
> URL: https://issues.apache.org/jira/browse/HDFS-16452
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namanode
> Affects Versions: 3.3.1
> Reporter: zhanghaobo
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 3h 20m
> Remaining Estimate: 0h
>
> In current ObserverReadProxyProvider implementation, we use the following
> code to invoke msync RPC.
> {code:java}
> getProxyAsClientProtocol(failoverProxy.getProxy().proxy).msync(); {code}
> But msync RPC maybe send to Observer NameNode in this way, and then failover
> to Active NameNode. This can be avoid by applying this patch.
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