[
https://issues.apache.org/jira/browse/HADOOP-4539?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12681830#action_12681830
]
Suresh Srinivas commented on HADOOP-4539:
-----------------------------------------
1. I think it might be a good idea to abstract the active/backup/checkpointer
as states of Namenode. This helps in transition of states back and forth. In
current design an active node cannot become backup. This can be done in a
separate jira.
Coding related:
bq. 6.1. I think that ServerCommand actions (static ints) should belong to the
commands that use them. I plan to file an issue to move DatanodeCommand actions
into the respective commands.
I am not clear on this. Since ACT_SHUTDOWN is part of protocol itself, it
should be in NamenodeProtocol.java?
bq. 8.3. dfs.backup.address and dfs.backup.http.address define the addresses
which the backup node starts on its rpc and http servers. You do not need to
change the configuration when the node transitions from backup to active.
Example. If you start DataNode on port 0, which means on any free port, you do
not change the config file after startup, right? Same with backup/active nodes.
My example is more like: Say you configure address X as active and address Y as
backup during install time. Now for some reason you want to start active node
on Y. At this time the addresses that Y tries to bind to address X. Similarly
starting backup on X will result in X trying to bind to address Y. So
irrespective of local address, the services start on configured addresses. I am
not sure this can be solved until we have node management as a part of HA that
can assign roles to the nodes. Nodes always bind to their local address and
start or transition to the role they are assigned.
> 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, 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.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
