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https://issues.apache.org/jira/browse/HBASE-17437?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15843630#comment-15843630
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Zach York commented on HBASE-17437:
-----------------------------------
[~enis] [~stack] Thanks for the reviews. I will update the patch today. Also,
thanks for explaining the fs redo project. I would love to help with that
effort (and try to get some of it out by HBase 2.0 if I have some good
reviewers ;) ).
I have been thinking about moving everything to HFileSystem and have a couple
approaches:
1) Naive approach: Move the getWALRootDirectory() and getWALFileSystem() to
HFileSystem and use them as they are being used right now.
This way is error-prone because people can forget to use the right FileSystem
in their changes (after this change) and break things.
2) Intelligent approach: Have HFileSystem override all the methods from
FileSystem and ensure that the correct FileSystem is used based off of the
scheme.
This way is much better, but might incur a small performance loss (should be
negligible though).
What do you guys think?
I will be implementing approach 1 to move complete this JIRA, but then would
like to do approach 2 in a follow-up JIRA.
> Support specifying a WAL directory outside of the root directory
> ----------------------------------------------------------------
>
> Key: HBASE-17437
> URL: https://issues.apache.org/jira/browse/HBASE-17437
> Project: HBase
> Issue Type: Improvement
> Components: Filesystem Integration, wal
> Affects Versions: 1.2.4
> Reporter: Yishan Yang
> Assignee: Zach York
> Labels: patch
> Fix For: 2.0.0, 1.4.0
>
> Attachments: hbase-17437-branch-1.2.patch,
> HBASE-17437.master.001.patch, HBASE-17437.master.002.patch,
> HBASE-17437.master.003.patch, HBASE-17437.master.004.patch,
> hbase-17437-master.patch
>
>
> Currently, the WAL and the StoreFiles need to be on the same FileSystem. Some
> FileSystems (such as Amazon S3) don’t support append or consistent writes.
> These two properties are imperative for the WAL in order to avoid loss of
> writes. However, StoreFiles don’t necessarily need the same consistency
> guarantees (since writes are cached locally and if writes fail, they can
> always be replayed from the WAL).
>
> This JIRA aims to allow users to configure a log directory (for WALs) that is
> outside of the root directory or even in a different FileSystem. The default
> value will still put the log directory under the root directory.
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