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https://issues.apache.org/jira/browse/HADOOP-4539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12681924#action_12681924
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Konstantin Shvachko commented on HADOOP-4539:
---------------------------------------------
S> ACT_SHUTDOWN is part of protocol itself, it should be in
NamenodeProtocol.java
Makes sense I moved all action codes into {{NamenodeProtocol}}.
About your address concerns: you in fact propose a change to how configuration
works.
You are saying that configuration should contain addresses {{rcp.address}} and
{{http.address}} which would be used by the server starting on this node no
matter what this server is. This is different from how things are in hadoop
now. With your approach you will have to create a separate configuration for
each server. Say for the name-node you will need to set local {{rcp.address =
X}} and {{http.address = Y}}, while for data-nodes you will have to move this
values to other variables {{namenode.rcp.address = X}} and
{{namenode.http.address = Y}} because {{rcp.address}} and {{http.address}}
should reflect the data-nodes' addresses.
We on the contrary were trying so far (as much as possible) to keep one
configuration for all servers: set everything in one config file and ssh it to
all servers and clients unmodified.
Well this task is not for this issue anyway.
N> Static variables sometimes are misused as global variables.
Exactly!
N> I suggest passing a FSNamesystem object in the constructor BackupStorage().
It's the other way around: Backup node constructs {{BackupStorage()}} first
then creates {{FSNamesystem}} with the BackupStorage as a parameter.
My idea with the comment you cited above was that while fixing HADOOP-5119 we
will make a member in FSImage referencing {{FSNamesystem}}, and a getter
{{getFSNamesystem()}}, which returns the reference. Then {{BackupStorage()}}
will require only one change - removing the method you cited.
> Streaming Edits to a Standby Name-Node.
> ---------------------------------------
>
> Key: HADOOP-4539
> URL: https://issues.apache.org/jira/browse/HADOOP-4539
> Project: Hadoop Core
> Issue Type: New Feature
> Components: dfs
> Reporter: Konstantin Shvachko
> Assignee: Konstantin Shvachko
> Fix For: 0.21.0
>
> Attachments: BackupNode.patch, BackupNode.patch, BackupNode.patch,
> BackupNode.patch, BackupNode.patch, image001.gif, StreamEditsToBN.pdf,
> StreamEditsToSNN.htm
>
>
> Currently Secondary name-node acts as mere checkpointer.
> Secondary name-node should be transformed into a standby name-node (SNN).
> The long term goal is to make it a warm standby.
> The purpose of this issue is to provide real time streaming of edits to SNN
> so that it contained the up-to-date namespace state.
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