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From "Manoj Govindassamy (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-10904) Need a new Result state for DiskBalancerWorkStatus to indicate the final Plan step errors and stuck rebalancing
Date Mon, 26 Sep 2016 18:47:20 GMT
Manoj Govindassamy created HDFS-10904:
-----------------------------------------

             Summary: Need a new Result state for DiskBalancerWorkStatus to indicate the final
Plan step errors and stuck rebalancing
                 Key: HDFS-10904
                 URL: https://issues.apache.org/jira/browse/HDFS-10904
             Project: Hadoop HDFS
          Issue Type: Sub-task
          Components: balancer & mover
    Affects Versions: 3.0.0-alpha2
            Reporter: Manoj Govindassamy
            Assignee: Manoj Govindassamy


* A DiskBalancer {{NodePlan}} might include a Single {{MoveStep}} or a list of MoveSteps to
perform the requested disk balancing operation.

* {{DiskBalancerWorkStatus}} tracks the current disk balancing operation status for the {{Plan}}
just submitted. 

* {{DiskBalancerWorkStatus#Result}} has following states and the state machine movement for
the {{currentResult}} state doesn't seem to be a driven totally from disk balancing operation.
Especially, the state movement to DONE is happening only upon QueryResult, which can be improved.

{code}
  /** Various result values. **/
  public enum Result {
    NO_PLAN(0),
    PLAN_UNDER_PROGRESS(1),
    PLAN_DONE(2),
    PLAN_CANCELLED(3);

DiskBalancer
cancelPlan(String)
        this.currentResult = Result.PLAN_CANCELLED;
DiskBalancer(String, Configuration, BlockMover)
    this.currentResult = Result.NO_PLAN;
queryWorkStatus()
        this.currentResult = Result.PLAN_DONE;
shutdown()
      this.currentResult = Result.NO_PLAN;
        this.currentResult = Result.PLAN_CANCELLED;
submitPlan(String, long, String, String, boolean)
      this.currentResult = Result.PLAN_UNDER_PROGRESS;
{code}


* More importantly, when the final {{MoveStep}} of the {{NodePlan}} fails, the currentResult
state is stuck in {{PLAN_UNDER_PROGRESS}} forever. User querying the status will assume the
operation is in progress when in reality its not making any progress.  User can also run {{Query}}
command with _verbose_ option which then will display more details about the operation which
includes details about errors encountered.
**  Query Output: {code}
Plan File:  <_file_path_>
Plan ID: <_plan_hash_>
Result: PLAN_UNDER_PROGRESS
{code}

** {code}
"sourcePath" : "/data/disk2/hdfs/dn",
  "destPath" : "/data/disk3/hdfs/dn",
  "workItem" :
    .. .. ..
    "errorCount" : 0,
    "errMsg" : null,
    .. .. 
    "maxDiskErrors" : 5,
    .. .. ..
{code}
** But, user has to decipher these details to make out that the disk balancing operation is
stuck as the top level Result still says {{PLAN_UNDER_PROGRESS}}. So, we want the DiskBalancer
differentiate between the in-progress operation and the stuck or final error operations.




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