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From "Andrew Wang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5358) add 'replication' field to PathBasedCacheDirective
Date Mon, 14 Oct 2013 21:23:47 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5358?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13794503#comment-13794503

Andrew Wang commented on HDFS-5358:

Thanks for splitting this out from HDFS-5096, nice to get that logical separation as well.

* Higher-level question, what do you think about a "cache all" replication factor that just
uses the underlying file's replication factor? I think 1 is a good default, but I could imagine
blowing up the replication factor of a small often-used table and also wanting it to be cached.
* Turning {{0}} into a {{public static final short MIN_REPLICATION = 1}} or (better) a {{validate()}}
check would make it easier if we later decide to reserve some numbers for special values like
"cache all"
* Any reason why the edit log loader is no longer using the unprotected functions? It should
be safe to skip the checks, which makes edit log replaying faster. If you do want to go with
this, we should get rid of the unprotected functions where possible / update the javadoc.

> add 'replication' field to PathBasedCacheDirective
> --------------------------------------------------
>                 Key: HDFS-5358
>                 URL: https://issues.apache.org/jira/browse/HDFS-5358
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: namenode
>    Affects Versions: HDFS-4949
>            Reporter: Colin Patrick McCabe
>            Assignee: Colin Patrick McCabe
>         Attachments: HDFS-5358-caching.001.patch
> Add a 'replication' field to PathBasedCacheDirective, so that administrators can configure
how many cached replicas of a block the cluster should try to maintain.

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