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https://issues.apache.org/jira/browse/HDFS-9314?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15014801#comment-15014801
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Xiao Chen commented on HDFS-9314:
---------------------------------
Thanks [~mingma] for the review, I'll be working on the next rev.
1 quick clarification: I thought about passing in {{rackMap}}, but that needs
to add the extra parameter to both {{chooseReplicaToDelete}} and
{{pickupReplicaSet}}.
- I guess {{@VisibleForTesting public chooseReplicaToDelete}} should be fine.
- But changing the {{protected pickupReplicaSet}} would require modifying all
subclasses of {{BlockPlacementPolicyDefault}}, which is marked as
{{@InterfaceAudience.Private}} so [no external subclasses are
expected|https://hadoop.apache.org/docs/r2.7.1/api/org/apache/hadoop/classification/InterfaceAudience.html].
So we'll just update all usages in current code and not worry about
compatibility.
Are we on the same page here?
> Improve BlockPlacementPolicyDefault's picking of excess replicas
> ----------------------------------------------------------------
>
> Key: HDFS-9314
> URL: https://issues.apache.org/jira/browse/HDFS-9314
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Ming Ma
> Assignee: Xiao Chen
> Attachments: HDFS-9314.001.patch, HDFS-9314.002.patch,
> HDFS-9314.003.patch
>
>
> The test case used in HDFS-9313 identified NullPointerException as well as
> the limitation of excess replica picking. If the current replicas are on
> {SSD(rack r1), DISK(rack 2), DISK(rack 3), DISK(rack 3)} and the storage
> policy changes to HOT_STORAGE_POLICY_ID, BlockPlacementPolicyDefault's won't
> be able to delete SSD replica.
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