[jira] [Created] (CASSANDRA-19707) Support Direct I/O for SSTable writing

["Sam Lightfoot (Jira)" <ji...@apache.org>]

Sam Lightfoot created CASSANDRA-19707:
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             Summary: Support Direct I/O for SSTable writing
                 Key: CASSANDRA-19707
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-19707
             Project: Cassandra
          Issue Type: Improvement
          Components: Local/SSTable
            Reporter: Sam Lightfoot


Based on the throughput improvements observed in CASSANDRA-18464, which introduced commit log Direct I/O support, it is logical to extend Direct I/O support to writing SSTables (specifically during memtable flushing and compaction).

The advantages of Direct I/O include consistent disk performance, as it eliminates reliance on the page cache for flushing dirty pages. This consistency is particularly beneficial during the writing of large SSTable files, such as during higher-tier compactions, as it prevents page cache thrashing. Additionally, Direct I/O reduces latency associated with double buffering, which occurs in both the application and the page cache.

This Jira ticket aims to initiate a discussion and gather feedback on this proposal. I am particularly interested in identifying any potential drawbacks that may affect specific workloads.

If the feature is agreed upon, extensive performance testing will be essential to evaluate its impact and determine its overall value.



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