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https://issues.apache.org/jira/browse/HDFS-7240?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15328259#comment-15328259
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Kai Zheng commented on HDFS-7240:
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Thanks all for the discussion and [~anu] for this nice summary.
bq. To support Erasure coding, SCM will have to return more than 3 machines,
let us say we were using 6 + 3 model of erasure coding then then a container is
spread across nine machines. Once we modify SCM to support this model, the
container client will have write data to the locations and update the RAFT
state with the metadata of this block.
This looks like to support the striping erasure coding in client when
putting/updating a k/v to the store, right? For small objects, the write will
trigger the relatively expensive work of coding and writing to 6+3 locations, I
would doubt about the performance/overhead and the benefit. For large objects,
it sounds fine. So like we did for striping files, users should also be able to
opt striping or not according to their bucket conditions, I guess.
In HDFS files, in addition to striping, there is another way to do erasure
coding in block level as discussed in HDFS-8030, mainly targeting to convert
old/cold data from replica into erasure coded for saving storage. In Ozone, how
about this approach? Would we have old/cold buckets that can be frozen and no
update any longer? I'm not sure about this from users' point of view, but we
might not reuse the same sets of buckets/containers across many years, right?
> Object store in HDFS
> --------------------
>
> Key: HDFS-7240
> URL: https://issues.apache.org/jira/browse/HDFS-7240
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Jitendra Nath Pandey
> Assignee: Jitendra Nath Pandey
> Attachments: Ozone-architecture-v1.pdf, Ozonedesignupdate.pdf,
> ozone_user_v0.pdf
>
>
> This jira proposes to add object store capabilities into HDFS.
> As part of the federation work (HDFS-1052) we separated block storage as a
> generic storage layer. Using the Block Pool abstraction, new kinds of
> namespaces can be built on top of the storage layer i.e. datanodes.
> In this jira I will explore building an object store using the datanode
> storage, but independent of namespace metadata.
> I will soon update with a detailed design document.
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