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https://issues.apache.org/jira/browse/HBASE-11927?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Apekshit Sharma updated HBASE-11927:
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Release Note:
Checksumming is cpu intensive. HBase computes additional checksums for HFiles
(hdfs does checksums too) and stores them inline with file data. During
reading, these checksums are verified to ensure data is not corrupted. This
patch tries to use Hadoop Native Library for checksum computation, if it’s
available, otherwise falls back to standard Java libraries. Instructions to
load NHL in HBase can be found here
(http://hbase.apache.org/book.html#hadoop.native.lib).
Default checksum algorithm has been changed from CRC32 to CRC32C primarily
because of two reasons: 1) CRC32C has better error detection properties, and 2)
New Intel processors have a dedicated instruction for crc32c computation
(SSE4.2 instruction set)*. This changes is fully backward compatible. Also,
users should not see any differences except decrease in cpu usage. To keep old
settings, set configuration ‘hbase.hstore.checksum.algorithm’ to ‘CRC32’.
* On linux, run 'cat /proc/cpuinfo’ and look for sse4_2 in list of flags to see
if your processor supports SSE4.2.
> Use Native Hadoop Library for HFile checksum (And flip default from CRC32 to
> CRC32C)
> ------------------------------------------------------------------------------------
>
> Key: HBASE-11927
> URL: https://issues.apache.org/jira/browse/HBASE-11927
> Project: HBase
> Issue Type: Bug
> Reporter: stack
> Assignee: Apekshit Sharma
> Attachments: HBASE-11927-v1.patch, HBASE-11927-v2.patch,
> HBASE-11927-v4.patch, HBASE-11927-v5.patch, HBASE-11927.patch,
> after-compact-2%.svg, after-randomWrite1M-0.5%.svg, before-compact-22%.svg,
> before-randomWrite1M-5%.svg, c2021.crc2.svg, c2021.write.2.svg,
> c2021.zip.svg, crc32ct.svg
>
>
> Up in hadoop they have this change. Let me publish some graphs to show that
> it makes a difference (CRC is a massive amount of our CPU usage in my
> profiling of an upload because of compacting, flushing, etc.). We should
> also make use of native CRCings -- especially the 2.6 HDFS-6865 and ilk -- in
> hbase but that is another issue for now.
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