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https://issues.apache.org/jira/browse/HBASE-6868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13461319#comment-13461319
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Lars Hofhansl commented on HBASE-6868:
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OK. If that is all true, then we only benefit if:
# dfs.client.read.shortcircuit = true
# dfs.client.read.shortcircuit.skip.checksum=true
# the block is local
In all cases we do not improve the number of IOs.
Can we just recommend then to enable the two setting above?
Problem is that then we'll lose checksumming for all locally read blocks...?
> 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
>
>
> 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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