[
https://issues.apache.org/jira/browse/HDFS-4453?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13569328#comment-13569328
]
Todd Lipcon commented on HDFS-4453:
-----------------------------------
Section 4: I think you have some typos there:
- you mean GetBlockLocalPathInfo, not GetBlockLocations
- you said 'clients' twice where I think one of them should read 'servers'
{code}
+ To configure short-circuit local reads, you will need to put
+ <<<libhadoop.so>>> in your <<<LD_LIBRARY_PATH>>>. You can check if you have
done
+ this by running
+
{code}
Users don't generally set this via {{LD_LIBRARY_PATH}}. Instead, it goes in the
appropriate directory inside the install tree. Do we have other docs already
about how to enable the native code? Might be better to refer to those.
----
- Regarding {{/var/lib/hadoop-hdfs}} vs {{/var/run/hadoop-hdfs}} -- why's it
problematic if /var/run is a tmpfs? We shouldn't need it to persist
cross-reboot, and /var/run is generally _not_ cleaned by a tmpwatch process.
tmpfs is also better in that it will continue to work even if a local disk dies.
- In the example config, I would not use the _PORT trick - it only really makes
sense for dev setups like the minicluster, and otherwise may just confuse the
user.
- Please specify that you need to set these two configurations both on clients
and on servers.
> Make a simple doc to describe the usage and design of the shortcircuit read
> feature
> -----------------------------------------------------------------------------------
>
> Key: HDFS-4453
> URL: https://issues.apache.org/jira/browse/HDFS-4453
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: datanode, hdfs-client
> Reporter: Brandon Li
> Assignee: Colin Patrick McCabe
> Attachments: HDFS-4453.001.patch, HDFS-4453.002.patch
>
>
> It would be nice to have a document to describe the configuration and design
> of this feature. Also its relationship with previous short circuit read
> implementation(HDFS-2246), for example, can they co-exist, or this one is
> planed to replaces HDFS-2246, or it can fall back on HDFS-2246 when unix
> domain socket is not supported.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
