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https://issues.apache.org/jira/browse/HBASE-5074?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13201614#comment-13201614
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Phabricator commented on HBASE-5074:
------------------------------------
dhruba has commented on the revision "[jira] [HBASE-5074] Support checksums in
HBase block cache".
Todd: I agree with you. It is messy that the HFileSystem interface is leaking
out to the unit tests. Instead, inside HFile, I can do something like this when
a Reader is created:
if (!fs instanceof HFileSystem) {
fs = new HFileSystem(fs);
}
what this means is that users of HFile that already passes in a HFileSystem
will get the new behaviour while. HReginServer anyways voluntarily creates
HFileSystem before invoking HFile, so it work.
I did not do this earlier because I thought that 'using reflection' is
costly, but on second thoughts the cost is not much because it will be done
only once when a new reader is created for the first time. what do you think?
REVISION DETAIL
https://reviews.facebook.net/D1521
> support checksums in HBase block cache
> --------------------------------------
>
> Key: HBASE-5074
> URL: https://issues.apache.org/jira/browse/HBASE-5074
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Attachments: D1521.1.patch, D1521.1.patch, D1521.2.patch,
> D1521.2.patch, D1521.3.patch, D1521.3.patch
>
>
> The current implementation of HDFS stores the data in one block file and the
> metadata(checksum) in another block file. This means that every read into the
> HBase block cache actually consumes two disk iops, one to the datafile and
> one to the checksum file. This is a major problem for scaling HBase, because
> HBase is usually bottlenecked on the number of random disk iops that the
> storage-hardware offers.
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