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https://issues.apache.org/jira/browse/CASSANDRA-7549?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14061991#comment-14061991
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Benedict commented on CASSANDRA-7549:
-------------------------------------
Can you clarify what this ticket is hoping to achieve? "Too small" compared to
what? The default Cassandra block size is 64Kb, and since currently reading
data in a block requires a sequential scan of data preceding the target record,
reading ~40Kb is about correct for reading a very small row with an 8Kb read
ahead, and zero page cache utilisation (i.e. completely random reads for a
substantially larger than memory dataset). Increasing block size is likely to
reduce performance for this kind of workload, not improve it.
> Heavy Disk Read I/O
> -------------------
>
> Key: CASSANDRA-7549
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7549
> Project: Cassandra
> Issue Type: Improvement
> Environment: Cassandra 2.0.6
> Reporter: Hanson
>
> We observed heavy disk Read I/O, sometimes almost ~100% disk I/O %util. The
> block size for Disk Read seems too small per “iostat”:
> - DB Query: ~40KB per read
> - SSTables Compaction : ~120KB per read
> Could it use larger block size for Disk Read? (from Cassandra or OS disk
> driver tuning)
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