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https://issues.apache.org/jira/browse/HDFS-3150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13243614#comment-13243614
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Todd Lipcon commented on HDFS-3150:
-----------------------------------
Mostly looks good, just some nits:
{code}
+ LOG.info("Opened streaming server at " + tmpPort);
{code}
This isn't the terminology used elsewhere. "Data transfer server" or "data
transceiver server" is better
----
{code}
// Connect to backup machine
+ final String dnName = targets[0].getName(connectToDnViaHostname);
{code}
I think better to call this {{mirrorName}} or {{mirrorAddrString}}
----
{code}
+ final String dnName = proxySource.getName(connectToDnViaHostname);
+ InetSocketAddress proxyAddr = NetUtils.createSocketAddr(dnName);
{code}
Similar here -- {{proxyDnName}} or {{proxyAddrString}}
> Add option for clients to contact DNs via hostname in branch-1
> --------------------------------------------------------------
>
> Key: HDFS-3150
> URL: https://issues.apache.org/jira/browse/HDFS-3150
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: data-node, hdfs client
> Reporter: Eli Collins
> Assignee: Eli Collins
> Attachments: hdfs-3150-b1.txt
>
>
> Per the document attached to HADOOP-8198, this is just for branch-1, and
> unbreaks DN multihoming. The datanode can be configured to listen on a bond,
> or all interfaces by specifying the wildcard in the dfs.datanode.*.address
> configuration options, however per HADOOP-6867 only the source address of the
> registration is exposed to clients. HADOOP-985 made clients access datanodes
> by IP primarily to avoid the latency of a DNS lookup, this had the side
> effect of breaking DN multihoming. In order to fix it let's add back the
> option for Datanodes to be accessed by hostname. This can be done by:
> # Modifying the primary field of the Datanode descriptor to be the hostname,
> or
> # Modifying Client/Datanode <-> Datanode access use the hostname field
> instead of the IP
> I'd like to go with approach #2 as it does not require making an incompatible
> change to the client protocol, and is much less invasive. It minimizes the
> scope of modification to just places where clients and Datanodes connect, vs
> changing all uses of Datanode identifiers.
> New client and Datanode configuration options are introduced:
> - {{dfs.client.use.datanode.hostname}} indicates all client to datanode
> connections should use the datanode hostname (as clients outside cluster may
> not be able to route the IP)
> - {{dfs.datanode.use.datanode.hostname}} indicates whether Datanodes should
> use hostnames when connecting to other Datanodes for data transfer
> If the configuration options are not used, there is no change in the current
> behavior.
> I'm doing something similar to #1 btw in trunk in HDFS-3144 - refactoring the
> use of DatanodeID to use the right field (IP, IP:xferPort, hostname, etc)
> based on the context the ID is being used in, vs always using the IP:xferPort
> as the Datanode's name, and using the name everywhere.
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