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https://issues.apache.org/jira/browse/HBASE-5954?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13754869#comment-13754869
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Lars Hofhansl commented on HBASE-5954:
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@haosdent, we can't break the laws of physics. :)
If you sync *every single edit* you'll see terrible performance, how can we
expect otherwise?
HBase (even without fsync) wants things in batches, in PE HTable is doing it's
default batching (2m batches), so that's where the cost is amortized.
Enabling sync behind writes should improve this too (since we're writing
immutable data), since by the time we issue the sync some data will already be
sync'ed.
Lastly, fsync is fsync (or rather fdatasync and friends since we're sync'ing
files and not filesystems)... Once executed, previously cached data is on disk
no matter what the filesystem chooses to cache during normal operations; only
barriers are needed for correctness (AFAIK).
> 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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