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Posted to hdfs-dev@hadoop.apache.org by "Weiwei Yang (JIRA)" <ji...@apache.org> on 2017/08/09 09:53:00 UTC

[jira] [Created] (HDFS-12283) Ozone: DeleteKey-5: Implement SCM DeletedBlockLog

Weiwei Yang created HDFS-12283:
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             Summary: 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: Weiwei Yang


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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