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https://issues.apache.org/jira/browse/HDFS-13139?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Abhishek Sakhuja resolved HDFS-13139.
-------------------------------------
    Resolution: Workaround

HDP default configuration had calculated non-HDFS reserved storage 
"dfs.du.datanode.reserved" (approx 3.5 %) on total disk for the lowest storage 
configured for a datanode (among the compute config groups) which had three 
drives and one drive was in TBs. Our default configuration to store data on 
datanode "dfs.datanode.data.dir" was pointing to a drive with lowest capacity 
(around 3 % of overall DN storage). This 3 % < 3.5 % had made HDFS capacity as 
0% and our existing datanode storage had some supporting directories and files 
in KBs which had resulted in marking negative KB capacity of the datanode. To 
fix the downscaling issue, either, we need to lower down non hdfs reserved 
capacity (lower than 3 %) or point our datanode to higher disk capacity 
(greater than 3.5 %).

> Default HDFS as Azure WASB tries rebalancing datanode data to HDFS (0% 
> capacity) and fails
> ------------------------------------------------------------------------------------------
>
>                 Key: HDFS-13139
>                 URL: https://issues.apache.org/jira/browse/HDFS-13139
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: datanode, fs/azure, hdfs
>    Affects Versions: 2.7.3
>            Reporter: Abhishek Sakhuja
>            Priority: Major
>              Labels: azureblob, cloudbreak, datanode, decommission, hdfs
>
> Configuring Azure WASB storage as a default HDFS location which means that 
> Hadoop HDFS capacity will be 0. I have default replication as 1 but now when 
> I am trying to decommission a node, datanode tries to rebalance some 28KB of 
> data to another available datanode. However, our HDFS has 0 capacity and 
> therefore, decommissioning fails with below given error:
> {code:java}
> New node(s) could not be removed from the cluster. Reason Trying to move 
> '28672' bytes worth of data to nodes with '0' bytes of capacity is not 
> allowed{code}
> Getting the information on cluster shows that default local HDFS is still 
> used for some KB space which is getting rebalanced whereas available capacity 
> is 0:
> {code:java}
> "CapacityRemaining" : 0,
>  "CapacityTotal" : 0,
>  "CapacityUsed" : 131072,
>  "DeadNodes" : "{}",
>  "DecomNodes" : "{}",
>  "HeapMemoryMax" : 1060372480,
>  "HeapMemoryUsed" : 147668152,
>  "NonDfsUsedSpace" : 0,
>  "NonHeapMemoryMax" : -1,
>  "NonHeapMemoryUsed" : 75319744,
>  "PercentRemaining" : 0.0,
>  "PercentUsed" : 100.0,
>  "Safemode" : "",
>  "StartTime" : 1518241019502,
>  "TotalFiles" : 1,
>  "UpgradeFinalized" : true,{code}



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