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https://issues.apache.org/jira/browse/HBASE-5954?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13755411#comment-13755411
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haosdent commented on HBASE-5954:
---------------------------------
When we use the hsync of HDFS, the JVM in datanode will call fsync or fdatasync
to ensure the dirty data of file is flush to stable storage. When I do the test
as same as [~lhofhansl], I have this test result:
Without WAL/HFile sync: ~13s
With WAL sync, Without HFile sync: ~120s (Sorry, I make some input mistakes
before.)
I think you may unclear about the differences between "data=writeback" and
"data=order, barrier=1". These posts may be help you understand them.
1.https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/writebarr.html
2.http://lwn.net/Articles/457667/
> Allow proper fsync support for HBase
> ------------------------------------
>
> Key: HBASE-5954
> URL: https://issues.apache.org/jira/browse/HBASE-5954
> Project: HBase
> Issue Type: Improvement
> Reporter: Lars Hofhansl
> Assignee: Lars Hofhansl
> Priority: Critical
> Fix For: 0.98.0
>
> Attachments: 5954-trunk-hdfs-trunk.txt, 5954-trunk-hdfs-trunk-v2.txt,
> 5954-trunk-hdfs-trunk-v3.txt, 5954-trunk-hdfs-trunk-v4.txt,
> 5954-trunk-hdfs-trunk-v5.txt, 5954-trunk-hdfs-trunk-v6.txt, hbase-hdfs-744.txt
>
>
> At least get recommendation into 0.96 doc and some numbers running w/ this
> hdfs feature enabled.
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