[
https://issues.apache.org/jira/browse/HDFS-4645?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13699048#comment-13699048
]
Tsz Wo (Nicholas), SZE commented on HDFS-4645:
----------------------------------------------
> The name "maxGenerationStampForLegacyBlocks" may be confusion since it is not
> really a "max". "stampAtIdSwitch" sounds better. Similarly, for
> get/setMaxSequentialBlockId.
Oops, I was confused. We have
{quote}
maxGenerationStampForLegacyBlocks = legacyGenerationStamp.getCurrentValue() +
HdfsConstants.RESERVED_GENERATION_STAMPS)
{quote}
So "maxGenerationStampForLegacyBlocks" actually is the limit of the generation
stamp value for the legacy blocks. However, we also have
"maxSequentialBlockId", it means the last allocated block id. These two "max"
values have different meaning. How about we drop "max" and call them
"generationStampLimitForLegacyBlocks" and "lastAllocatedBlockId"?
BTW, we need to check generation stamp limit for legacy blocks in
getNextLegacyGenerationStamp().
> Move from randomly generated block ID to sequentially generated block ID
> ------------------------------------------------------------------------
>
> Key: HDFS-4645
> URL: https://issues.apache.org/jira/browse/HDFS-4645
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 3.0.0
> Reporter: Suresh Srinivas
> Assignee: Arpit Agarwal
> Attachments: editsStored, HDFS-4645.001.patch, HDFS-4645.002.patch,
> HDFS-4645.003.patch, HDFS-4645.004.patch, HDFS-4645.005.patch,
> SequentialblockIDallocation.pdf
>
>
> Currently block IDs are randomly generated. This means there is no pattern to
> block ID generation and no guarantees such as uniqueness of block ID for the
> life time of the system can be made. I propose using SequentialNumber for
> block ID generation.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
