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https://issues.apache.org/jira/browse/HDFS-7770?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14510553#comment-14510553
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Akira AJISAKA commented on HDFS-7770:
-------------------------------------
Thanks [~xyao] for the patch. Two comments:
{code}
+ 4. A datanode storage location /grid/dn/ram0 on ARCHIVE should be
configured with `[RAM_DISK]file:///grid/dn/ram0`
{code}
1. ARCHIVE should be RAM_DISK.
{code}
+ The default storage type of a datanode storage location will be DISK if it
does not have a storage type tagged explicitly.
{code}
2. I'm thinking it's better to document how to tag a storage type explicitly.
> Need document for storage type label of data node storage locations under
> dfs.data.dir
> --------------------------------------------------------------------------------------
>
> Key: HDFS-7770
> URL: https://issues.apache.org/jira/browse/HDFS-7770
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 2.6.0
> Reporter: Xiaoyu Yao
> Assignee: Xiaoyu Yao
> Attachments: HDFS-7770.00.patch
>
>
> HDFS-2832 enables support for heterogeneous storages in HDFS, which allows DN
> as a collection of storages with different types. However, I can't find
> document on how to label different storage types from the following two
> documents. I found the information from the design spec. It will be good we
> document this for admins and users to use the related Archival storage and
> storage policy features.
> http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/ArchivalStorage.html
> http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/hdfs-default.xml
> This JIRA is opened to add document for the new storage type labels.
> 1. Add an example under ArchivalStorage.html#Configuration section:
> {code}
> <property>
> <name>dfs.data.dir</name>
> <value>[DISK]file:///hddata/dn/disk0,
> [SSD]file:///hddata/dn/ssd0,[ARCHIVE]file:///hddata/dn/archive0</value>
> </property>
> {code}
> 2. Add a short description of [DISK/SSD/ARCHIVE/RAM_DISK] options in
> hdfs-default.xml#dfs.data.dir and document DISK as storage type if no storage
> type is labeled in the data node storage location configuration.
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