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https://issues.apache.org/jira/browse/HBASE-5930?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13561739#comment-13561739
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Lars Hofhansl commented on HBASE-5930:
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How can deferred log flush ever be as fast as not writing the WAL at all?
Considering only the latency of a single request that might be true in many
cases, but it will definitely not be true on a busy cluster since all data is
written to the disks twice.
> Periodically flush the Memstore?
> --------------------------------
>
> Key: HBASE-5930
> URL: https://issues.apache.org/jira/browse/HBASE-5930
> Project: HBase
> Issue Type: Improvement
> Reporter: Lars Hofhansl
> Assignee: Devaraj Das
> Priority: Minor
> Fix For: 0.96.0
>
> Attachments: 5930-1.patch, 5930-wip.patch
>
>
> A colleague of mine ran into an interesting issue.
> He inserted some data with the WAL disabled, which happened to fit in the
> aggregate Memstores memory.
> Two weeks later he a had problem with the HDFS cluster, which caused the
> region servers to abort. He found that his data was lost. Looking at the log
> we found that the Memstores were not flushed at all during these two weeks.
> Should we have an option to flush memstores periodically. There are obvious
> downsides to this, like many small storefiles, etc.
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