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https://issues.apache.org/jira/browse/HDFS-3990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13631357#comment-13631357
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Jagane Sundar commented on HDFS-3990:
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Here is another instance of this problem.
Here is what I am trying to do:
Create a single VM developer environment that runs all daemons in a VM. The VM
gets a DHCP IP address, but there is no hostname associated with the IP
address. I configure hadoop using the DHCP IP address (e.g. 192.168.1.94)
instead of the hostname, or 'localhost' or '127.0.0.1]'. Datanode registration
fails because of this check.
HDFS-4269 creates an escape hatch just for 127.0.0.1. That does not solve my
problem because I want to use the DHCP address 192.168.1.94. I want to use
192.168.1.94 because I want to be able to access this VM from my host OS, or
from other machines in the network (if I use bridged networking in the virtual
NIC configuration).
I don't quite follow the original reasoning behind this check. Is there some
fundamental reason why HDFS cannot operate in an environment where the IP
address of the host cannot be resolved to a hostname?
> NN's health report has severe performance problems
> --------------------------------------------------
>
> Key: HDFS-3990
> URL: https://issues.apache.org/jira/browse/HDFS-3990
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 0.23.0, 2.0.0-alpha, 3.0.0
> Reporter: Daryn Sharp
> Assignee: Daryn Sharp
> Priority: Critical
> Fix For: 3.0.0, 2.0.3-alpha, 0.23.5
>
> Attachments: HDFS-3990.branch-0.23.patch,
> HDFS-3990.branch-0.23.patch, HDFS-3990.patch, HDFS-3990.patch,
> HDFS-3990.patch, HDFS-3990.patch, HDFS-3990.patch, HDFS-3990.patch,
> HDFS-3990.patch, HDFS-3990.patch, hdfs-3990.txt, hdfs-3990.txt
>
>
> The dfshealth page will place a read lock on the namespace while it does a
> dns lookup for every DN. On a multi-thousand node cluster, this often
> results in 10s+ load time for the health page. 10 concurrent requests were
> found to cause 7m+ load times during which time write operations blocked.
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