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https://issues.apache.org/jira/browse/HBASE-6868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13462440#comment-13462440
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stack commented on HBASE-6868:
------------------------------
+1 on patch. Default is let hdfs worry about checksums. No chance of
dbl-checksumming. If you did enable HBASE-5074 hbase checksums and also
enabled shortcircuit, you should be good (you'll be doing an unwanted extra
seek if you have to do a non-local until hdfs-3429 goes in but thats another
issue). Your setting of dfs.client.read.shortcircuit.skip.checksum on the
hfile fs, will make it so we avoid a dbl-checksum. The new Configuration is
important before you set the boolean as you have it. I think this is good for
trunk and 0.94.
We should test starting a 0.94.2 on top of data written when the flag was true
to see if we skip over the hbase inserted checksums.
I can write a little note for the refguide on this after goes in. Will also
look at verifying it.
> Skip checksum is broke; are we double-checksumming by default?
> --------------------------------------------------------------
>
> Key: HBASE-6868
> URL: https://issues.apache.org/jira/browse/HBASE-6868
> Project: HBase
> Issue Type: Bug
> Components: HFile, wal
> Affects Versions: 0.94.0, 0.94.1
> Reporter: LiuLei
> Priority: Blocker
> Fix For: 0.94.3, 0.96.0
>
> Attachments: 6868-0.96-idea.txt, 6868-0.96-v2.txt, 6868-0.96-v3.txt
>
>
> The HFile contains checksums for decrease the iops, so when Hbase read HFile
> , that dont't need to read the checksum from meta file of HDFS. But HLog
> file of Hbase don't contain the checksum, so when HBase read the HLog, that
> must read checksum from meta file of HDFS. We could add setSkipChecksum per
> file to hdfs or we could write checksums into WAL if this skip checksum
> facility is enabled
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