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https://issues.apache.org/jira/browse/HDFS-12918?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Manoj Govindassamy resolved HDFS-12918.
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Resolution: Won't Fix
We have an upgrade incompatible fix landed in C6 at
e565b5277d5b890dad107fe85e295a3907e4bfc1. The fix is necessary and it verifies
the EC Policy state when loading FSImage. This issue is nothing to do with the
default value for the ECPolicyState field in the ErasureCodingPolicyProto.
While the ECPolicyState field is optional in ECPolocyProto message for over the
wire communications, but its mandatory in FSImage for the EC files. I hope the
upgrade incompatible changes before the C6 GA are ok. Please let me know if you
have other thoughts.
> NameNode fails to start after upgrade - Missing state in ECPolicy Proto
> ------------------------------------------------------------------------
>
> Key: HDFS-12918
> URL: https://issues.apache.org/jira/browse/HDFS-12918
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs
> Affects Versions: 3.0.0-beta1
> Reporter: Zach Amsden
> Assignee: Manoj Govindassamy
> Priority: Critical
>
> According to documentation and code comments, the default setting for erasure
> coding policy is disabled:
> /** Policy is disabled. It's policy default state. */
> DISABLED(1),
> However, HDFS-12258 appears to have incorrectly set the policy state in the
> protobuf to enabled:
> {code:java}
> message ErasureCodingPolicyProto {
> ooptional string name = 1;
> optional ECSchemaProto schema = 2;
> optional uint32 cellSize = 3;
> required uint32 id = 4; // Actually a byte - only 8 bits used
> + optional ErasureCodingPolicyState state = 5 [default = ENABLED];
> }
> {code}
> This means the parameter can't actually be optional, it must always be
> included, and existing serialized data without this optional field will be
> incorrectly interpreted as having erasure coding enabled.
> This unnecessarily breaks compatibility and will require existing HDFS
> installations that store metadata in protobufs to require reformatting.
> It looks like a simple mistake that was overlooked in code review.
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