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https://issues.apache.org/jira/browse/HDFS-12283?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16131652#comment-16131652
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Weiwei Yang commented on HDFS-12283:
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Hi [~anu]
bq. At least for the short term, yes. Let us say we take the option of going
with -1, what happens when a delete fails, I don't think we have come up with a
good strategy to handle this case yet.
We will need some tool to fix *corrupted* blocks in feature, in case datanode
could not remove them (e.g in case of metadata broken), some sort of purge
command to remove those stuff forcibly. I agree to have a big retry limit for
now. That gives us at least the choice to dump the DB and see how many dirty
entries are there, so admin could manually fix up things.
> Ozone: DeleteKey-5: Implement SCM DeletedBlockLog
> -------------------------------------------------
>
> Key: HDFS-12283
> URL: https://issues.apache.org/jira/browse/HDFS-12283
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ozone, scm
> Reporter: Weiwei Yang
> Assignee: Yuanbo Liu
> Attachments: HDFS-12283.001.patch, HDFS-12283-HDFS-7240.001.patch,
> HDFS-12283-HDFS-7240.002.patch, HDFS-12283-HDFS-7240.003.patch
>
>
> The DeletedBlockLog is a persisted log in SCM to keep tracking container
> blocks which are under deletion. It maintains info about under-deletion
> container blocks that notified by KSM, and the state how it is processed. We
> can use RocksDB to implement the 1st version of the log, the schema looks like
> ||TxID||ContainerName||Block List||ProcessedCount||
> |0|c1|b1,b2,b3|0|
> |1|c2|b1|3|
> |2|c2|b2, b3|-1|
> Some explanations
> # TxID is an incremental long value transaction ID for ONE container and
> multiple blocks
> # Container name is the name of the container
> # Block list is a list of block IDs
> # ProcessedCount is the number of times SCM has sent this record to datanode,
> it represents the "state" of the transaction, it is in range of \[-1, 5\], -1
> means the transaction eventually failed after some retries, 5 is the max
> number times of retries.
> We need to define {{DeletedBlockLog}} as an interface and implement this with
> RocksDB {{MetadataStore}} as the first version.
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