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https://issues.apache.org/jira/browse/HDFS-7866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15048347#comment-15048347
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Rui Li commented on HDFS-7866:
------------------------------
I tried to add another system policy (with different schema) and hit the
following problem.
In {{FSDirErasureCodingOp::getErasureCodingPolicyForPath}}, if the inode is a
file, we retrieve the policy by a numeric ID:
{{INodeFile::getErasureCodingPolicyID}}.
For directories however, the policy is retrieved by name:
{code}
final XAttrFeature xaf = inode.getXAttrFeature();
if (xaf != null) {
XAttr xattr = xaf.getXAttr(XATTR_ERASURECODING_POLICY);
if (xattr != null) {
ByteArrayInputStream bIn = new
ByteArrayInputStream(xattr.getValue());
DataInputStream dIn = new DataInputStream(bIn);
String ecPolicyName = WritableUtils.readString(dIn);
return fsd.getFSNamesystem().getErasureCodingPolicyManager().
getPolicy(ecPolicyName);
}
}
{code}
Therefore the newly added policy works for dirs but not files. I think we need
a unified way to store/get a policy. Any thoughts?
> Erasure coding: NameNode manages EC schemas
> -------------------------------------------
>
> Key: HDFS-7866
> URL: https://issues.apache.org/jira/browse/HDFS-7866
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Kai Zheng
> Assignee: Rui Li
> Attachments: HDFS-7866-v1.patch, HDFS-7866-v2.patch,
> HDFS-7866-v3.patch
>
>
> This is to extend NameNode to load, list and sync predefine EC schemas in
> authorized and controlled approach. The provided facilities will be used to
> implement DFSAdmin commands so admin can list available EC schemas, then
> could choose some of them for target EC zones.
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