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https://issues.apache.org/jira/browse/HDFS-13286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16461275#comment-16461275
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Erik Krogen edited comment on HDFS-13286 at 5/2/18 5:28 PM:
------------------------------------------------------------
Hey [~csun], sorry for taking a while to get back to you on this. Your new
{{HAServiceState}} changes inspired me to do a more comprehensive look at how
those states are used and I noticed a few things:
* Take a look at {{BPServiceActor}} L905-909. I haven't looked at HDFS-9917
yet, but judging from the comment it seems we probably want to change this
if-condition to {{state == HAServiceState.STANDBY || state ==
HAServiceState.OBSERVER}}. Can you see if you agree?
* The constructor of {{StandbyState}} needs to be modified to
{{super(isObserver ? HAServiceState.OBSERVER : HAServiceState.STANDBY);}}
instead of just always passing {{STANDBY}}, else things which use
{{HAState#getServiceState()}} will be wrong (see for example
{{NameNode#getServiceStatus()}}).
* It looks like we also need to update the enums in
{{FederationNamenodeServiceState}} and {{NNHAStatusHeartbeatProto}}, and their
associated usages
* We should be able to remove the TODO on {{NameNode}} L1866?
* I think this section of {{FailoverController#preFailoverChecks()}} may need
some work:
{code}
if (!toSvcStatus.getState().equals(HAServiceState.STANDBY)) {
throw new FailoverFailedException(
"Can't failover to an active service");
}
if (!toSvcStatus.isReadyToBecomeActive()) {
String notReadyReason = toSvcStatus.getNotReadyReason();
if (!forceActive) {
throw new FailoverFailedException(
target + " is not ready to become active: " +
notReadyReason);
} else {
LOG.warn("Service is not ready to become active, but forcing: {}",
notReadyReason);
}
}
{code}
It seems the first if-condition is assuming there are only two possible states,
so if the state is not STANDBY, it must be ACTIVE. I think we should update
this to explicitly check for ACTIVE. Next, is the service is in OBSERVER state,
{{isReadyToBecomeActive()}} will be false. In this case,
{{FailoverController#preFailoverChecks()}} will still allow this operation if
{{forceActive}} is true. I don't think we want to allow {{forceActive}} to
attempt to failover an observer, right?
* For all three usages of {{FSNameystem#isInStandbyState()}}, it actually seems
to me that they should apply if it is in observer or standby state, can you
double check and if so update accordingly?
was (Author: xkrogen):
Hey [~csun], sorry for taking a while to get back to you on this. Your new
{{HAServiceState}} changes inspired me to do a more comprehensive look at how
those states are used and I noticed a few things:
* Take a look at {{BPServiceActor}} L905-909. I haven't looked at HDFS-9917
yet, but judging from the comment it seems we probably want to change this
if-condition to {{state == HAServiceState.STANDBY || state ==
HAServiceState.OBSERVER}}. Can you see if you agree?
* The constructor of {{StandbyState}} needs to be modified to
{{super(isObserver ? HAServiceState.OBSERVER : HAServiceState.STANDBY);}}
instead of just always passing {{STANDBY}}, else things which use
{{HAState#getServiceState()}} will be wrong (see for example
{{NameNode#getServiceStatus()}}).
* It looks like we also need to update the enums in
{{FederationNamenodeServiceState}} and {{NNHAStatusHeartbeatProto}}, and their
associated usages
* We should be able to remove the TODO on {{NameNode}} L1866?
> Add haadmin commands to transition between standby and observer
> ---------------------------------------------------------------
>
> Key: HDFS-13286
> URL: https://issues.apache.org/jira/browse/HDFS-13286
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Chao Sun
> Assignee: Chao Sun
> Priority: Major
> Attachments: HDFS-13286-HDFS-12943.000.patch,
> HDFS-13286-HDFS-12943.001.patch, HDFS-13286-HDFS-12943.002.patch,
> HDFS-13286-HDFS-12943.003.patch, HDFS-13286-HDFS-12943.004.patch
>
>
> As discussed in HDFS-12975, we should allow explicit transition between
> standby and observer through haadmin command, such as:
> {code}
> haadmin -transitionToObserver
> {code}
> Initially we should support transition from observer to standby, and standby
> to observer.
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