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https://issues.apache.org/jira/browse/HDFS-11886?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16027344#comment-16027344
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Tsz Wo Nicholas Sze commented on HDFS-11886:
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> ... Since Ozone is an object store, I am rethinking my position and I am
> thinking that a key is visible to other users if and only if it is committed
> successfully.
+1
> This means that we would need two rpc calls for a putKey ...
When these two RPCs are invoked? Before step 1 and after step 3 in the
description?
In HDFS, DNs send block receipts to NN. I wonder if we should do something
similar in Ozone.
> Ozone : improve error handling for putkey operation
> ---------------------------------------------------
>
> Key: HDFS-11886
> URL: https://issues.apache.org/jira/browse/HDFS-11886
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ozone
> Reporter: Chen Liang
>
> Ozone's putKey operations involve a couple steps:
> 1. KSM calls allocateBlock to SCM, writes this info to KSM's local metastore
> 2. allocatedBlock gets returned to client, client checks to see if container
> needs to be created on datanode, if yes, create the container
> 3. writes the data to container.
> it is possible that 1 succeeded, but 2 or 3 failed, in this case there will
> be an entry in KSM's local metastore, but the key is actually nowhere to be
> found. We need to revert 1 is 2 or 3 failed in this case.
> To resolve this, we need at least two things to be implemented first.
> 1. We need deleteKey() to be added KSM first.
> 2. We also need container reports to be implemented first such that SCM can
> track whether the container is actually added.
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