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https://issues.apache.org/jira/browse/HBASE-5074?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13214107#comment-13214107
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Phabricator commented on HBASE-5074:
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stack has commented on the revision "[jira] [HBASE-5074] Support checksums in
HBase block cache".
Dhruba, have you been running this patch anywhere?
I'm +1 on commit if tests pass. If its not been run anywhere, i can test it
local before committing.
INLINE COMMENTS
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:235 Is it odd
that we only take in the minor version here and not major too?
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:861 Why WARN?
This is a 'normal' operation?
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1235 So, yeah,
aren't we doubling the FDs when we do this? The iops may be the same but the
threads floating in the datanode for reading will double?
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1244 I'm not
getting why no major version in here.
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1584 So, again
we are defaulting true (though it seems that if no checksums in hfiles, we'll
flip this flag to off pretty immediately)
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1589 Smile.
Like now.
src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java:1630 Extreme
nit: Should we close the nochecksumistream if its not going to be used?
Hmm... now I see we can flip back to using them again later in the stream
src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java:961 Now
we have our own filesystem, we can dump a bunch of crud in there ! We can add
things like the hbase.version check, etc. (joke -- sortof).
src/main/java/org/apache/hadoop/hbase/regionserver/RegionServerServices.java:86
I'm reluctant adding stuff to this Interface but I think this method qualifies
as important enough to be allowed in.
src/main/java/org/apache/hadoop/hbase/util/ChecksumType.java:70 Great
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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