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https://issues.apache.org/jira/browse/HBASE-5074?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13201569#comment-13201569
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Phabricator commented on HBASE-5074:
------------------------------------
mbautin has commented on the revision "[jira] [HBASE-5074] Support checksums in
HBase block cache".
@dhruba; thanks for the fixes! Here are some more comments (I still have to
go through the last 25% of the new version of the patch).
INLINE COMMENTS
src/main/java/org/apache/hadoop/hbase/io/hfile/FixedFileTrailer.java:119
Please address this comment. The javadoc says "major" and the variable name
says "minor".
src/main/java/org/apache/hadoop/hbase/io/hfile/FixedFileTrailer.java:49
Please correct the misspelling.
src/main/java/org/apache/hadoop/hbase/io/hfile/FixedFileTrailer.java:352 I
think this function needs to be renamed to expectAtLeastMajorVersion for clarity
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:287 I think we
should either consistently use the onDiskSizeWithHeader field or get rid of it.
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterV1.java:220 Please
do use a constant instead of "0" here for the minor version.
src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java:3551 Long line
src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:60 This lazy
initialization is not thread-safe. This also applies to other enum members
below. Can the meth field be initialized on the enum constructor, or do we rely
on some classes being loaded by the time this initialization is invoked?
src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:63-67 Avoid
repeating "org.apache.hadoop.util.PureJavaCrc32" three times in string form
src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:74-75 Avoid
repeating the "java.util.zip.CRC32" string
src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:98-99 Avoid
repeating the string
src/test/java/org/apache/hadoop/hbase/io/hfile/TestChecksum.java:132 Fix
indentation
src/test/java/org/apache/hadoop/hbase/io/hfile/TestChecksum.java:174 Fix
indentation
src/test/java/org/apache/hadoop/hbase/io/hfile/TestChecksum.java:71
Inconsistent formatting: "1024 +980".
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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