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https://issues.apache.org/jira/browse/HDFS-1974?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Suresh Srinivas updated HDFS-1974:
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Attachment: HDFS-1974.3.patch
Thanks for the comments. I have addressed most of them in the new patch.
bq. public static boolean isHAEnabled(Configuration conf) - is the intention
that this will return true if HA is enabled on the cluster? yes
bq. this.state = DFSUtil.isHAEnabled(conf) ? ACTIVE_STATE : STANDBY_STATE; -
should probably be replaced with a TODO. It's obviously not reasonable to have
both NNs start as active just because HA is enabled. There needs to be some
leader determination.
I meant !isHAEnabled, then retain the older functionality. New patch addresses
it.
bq. UnsupportedActionException seems redundant with o.a.h.ipc.StandbyException.
How do you handle operations related to checkpointing and journaling that
namenode in it's various states/roles cannot satisfy?
Further we need to think if StandbyException should be at IPC layer? Is this
not Service related exception?
bq. I don't understand the purpose of having both HAState.setState and
HAState.(standbyToActive|activeToStandby). Shouldn't just setState be
sufficient?
Setting a state involves multiple steps - that existing current state and
entering a new state. standbyToActive and activeToStandby are interface methods.
bq. In HAState.setState, you have exitState(nn); s.enterState(nn);. What state
should the NN be considered to be in between these calls?
exitState does the cleanup required for exiting a state, with in the state. I
have made a change to set the state of NN before enterState.
> HA: Introduce active and standby states to the namenode
> -------------------------------------------------------
>
> Key: HDFS-1974
> URL: https://issues.apache.org/jira/browse/HDFS-1974
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: name-node
> Reporter: Suresh Srinivas
> Assignee: Suresh Srinivas
> Attachments: HDFS-1974.1.patch, HDFS-1974.2.patch, HDFS-1974.3.patch,
> HDFS-1974.patch
>
>
> Currently namenode supports active, secondary and backup roles. To support
> namenode high availability, active and standby states are needed. Note that
> this is different from the existing notion of namenode role, where a namenode
> cannot transition from one role to the other.
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