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https://issues.apache.org/jira/browse/HDFS-1751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13008216#comment-13008216
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Jakob Homan commented on HDFS-1751:
-----------------------------------
First off, this JIRA is named incorrectly. The intrinsic limits on HDFS files
and directories are a function of namenode memory and our ability to address
inodes. What's being proposed is an optional setting, so by definition, it's
not intrinsic. Instead, what's being suggested is a quota (synonym: limit) on
the number of files created in a single directory, which translated to
class-speak would be NSPerDirectoryFileQuota. A case can be made that this
would be a good quota to have, in addition to the existing NSQuota. Nestled
cozily amongst the other quotas, it would make sense. But implemented with a
different name and separated in the code from its fellows, it's error prone and
confusing.
bq. (I'll avoid the design dispute, and explain why the implementation is the
way it is)
The actual implementation is much less important than how this is exposed to
the user. Adding an extra parameter to updateCount is fine if it is in aid of
getting the correct implementation of this feature.
bq. It is like 'ulimit' and quota on a unix system. They solve different
problems.
Not really. I was fully expecting another JIRA to implement ulimit-like
functionality to prevent users from opening millions of files at the same,
which may be reasonable but is orthogonal to this.
> Intrinsic limits for HDFS files, directories
> --------------------------------------------
>
> Key: HDFS-1751
> URL: https://issues.apache.org/jira/browse/HDFS-1751
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: data-node
> Affects Versions: 0.22.0
> Reporter: Daryn Sharp
> Assignee: Daryn Sharp
> Fix For: 0.23.0
>
> Attachments: HDFS-1751-2.patch, HDFS-1751-3.patch, HDFS-1751-4.patch,
> HDFS-1751.patch
>
>
> Enforce a configurable limit on:
> the length of a path component
> the number of names in a directory
> The intention is to prevent a too-long name or a too-full directory. This is
> not about RPC buffers, the length of command lines, etc. There may be good
> reasons for those kinds of limits, but that is not the intended scope of this
> feature. Consequently, a reasonable implementation might be to extend the
> existing quota checker so that it faults the creation of a name that violates
> the limits. This strategy of faulting new creation evades the problem of
> existing names or directories that violate the limits.
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