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https://issues.apache.org/jira/browse/HDFS-2832?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13814025#comment-13814025
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Arpit Agarwal commented on HDFS-2832:
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Konstantin, UUID generation uses a cryptographically secure PRNG. On Linux this
is /dev/random, the fallback is SHA1PRNG with a period of 2^160.
With a billion nodes the probability of a collision in a 128-bit space is less
than 1 in 10^20. Note that what was previously the storageID is now the
datanode UUID and it is generated once for the lifetime of a datanode.
> Enable support for heterogeneous storages in HDFS
> -------------------------------------------------
>
> Key: HDFS-2832
> URL: https://issues.apache.org/jira/browse/HDFS-2832
> Project: Hadoop HDFS
> Issue Type: New Feature
> Affects Versions: 0.24.0
> Reporter: Suresh Srinivas
> Assignee: Suresh Srinivas
> Attachments: 20130813-HeterogeneousStorage.pdf, h2832_20131023.patch,
> h2832_20131023b.patch, h2832_20131025.patch, h2832_20131028.patch,
> h2832_20131028b.patch, h2832_20131029.patch, h2832_20131103.patch,
> h2832_20131104.patch
>
>
> HDFS currently supports configuration where storages are a list of
> directories. Typically each of these directories correspond to a volume with
> its own file system. All these directories are homogeneous and therefore
> identified as a single storage at the namenode. I propose, change to the
> current model where Datanode * is a * storage, to Datanode * is a collection
> * of strorages.
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