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https://issues.apache.org/jira/browse/HBASE-20951?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16796115#comment-16796115
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Josh Elser commented on HBASE-20951:
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bq. The goal of this project is to separate WAL from HDFS and store it into a
log service to achieve lower cost and flexibility in cloud compare to
HDFS(decommission is panic as said in the doc). But, what is the storage for
this log service? Local disks in EC2 instance?
Correct. The "WAL data" would really become the RAFT log which is stored on
local disk.
bq. How to achieve the goal of flexibility itself？Does it mean that we need to
maintain another cluster for this log service?
Nope. The "novel" part of Ratis is that it is a library that we would embed,
not another service that we need to run. Meaning, we would be able to keep
everything inside of HBase already.
bq. isn't it panic too when decommissioning?
Yes, the big difference operationally is that we would have to be much more
careful about losing nodes, whereas we don't really care if a lot of RS
disappear all at once. If we lose too many RS, we would potentially be unable
to read a recently written WAL.
Does that help? Happy to answer any questions :)
> Ratis LogService backed WALs
> ----------------------------
>
> Key: HBASE-20951
> URL: https://issues.apache.org/jira/browse/HBASE-20951
> Project: HBase
> Issue Type: New Feature
> Components: wal
> Reporter: Josh Elser
> Assignee: Josh Elser
> Priority: Major
>
> Umbrella issue for the Ratis+WAL work:
> Design doc:
> [https://docs.google.com/document/d/1Su5py_T5Ytfh9RoTTX2s20KbSJwBHVxbO7ge5ORqbCk/edit#|https://docs.google.com/document/d/1Su5py_T5Ytfh9RoTTX2s20KbSJwBHVxbO7ge5ORqbCk/edit]
> The (over-simplified) goal is to re-think the current WAL APIs we have now,
> ensure that they are de-coupled from the notion of being backed by HDFS, swap
> the current implementations over to the new API, and then wire up the Ratis
> LogService to the new WAL API.
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