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https://issues.apache.org/jira/browse/HBASE-5074?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13215108#comment-13215108
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Phabricator commented on HBASE-5074:
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dhruba has commented on the revision "[jira] [HBASE-5074] Support checksums in
HBase block cache".
INLINE COMMENTS
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:235 This
constructor is used only for V2, hence the major number is not a parameter.
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1235 I think
there won;t be any changes to the number of threads in the datanode. A datanode
thread is not tied up with a client FileSystem object. Instead, a global pool
of threads in the datanode are free to serve any read-requests from any client
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1244 The minor
version indicates disk-format changes inside an HFileBlock. The major version
indicates disk-format changes within a entire HFile. Since the AbstractFSReader
only reads HFileBlocks, so it is logical that it contains the minorVersion, is
it not?
But I can put in the majorVersion in it as well, if you so desire.
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1584 Yes, the
default it to enable hbase-checksum verification. And you are right that if the
hfile is of the older type, then we will quickly flip this back to false (in
the next line)
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1630 I think
we should keep both streams active till the HFile itself is closed.
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1646 done
src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java:961
Yes, precisely. Going forward, I would like to see if we can make HLogs go to a
filesystem object that is different from the filesystem used for hfiles.
src/main/java/org/apache/hadoop/hbase/regionserver/RegionServerServices.java:86
I agree with you completely. This is an interface that should not change often.
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, D1521.4.patch, D1521.4.patch,
> D1521.5.patch, D1521.5.patch, D1521.6.patch, D1521.6.patch, D1521.7.patch,
> D1521.7.patch, D1521.8.patch, D1521.8.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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