Sam Lightfoot created CASSANDRA-21393:
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Summary: Investigate: Add FDP (Flexible Data Placement) hints to
write paths to reduce SSD write amplification
Key: CASSANDRA-21393
URL: https://issues.apache.org/jira/browse/CASSANDRA-21393
Project: Apache Cassandra
Issue Type: Improvement
Components: Local/SSTable
Reporter: Sam Lightfoot
Assignee: Sam Lightfoot
Fix For: 6.x
Follow-up from the implementation for compaction reads (CASSANDRA-19987)
Notable points
* Update the start-up check that impacts DIO writes
({_}checkKernelBug1057843{_})
* RocksDB uses 1 MB flush buffer. This should be configurable and performance
tested (256KB vs 1MB)
* Introduce compaction_write_disk_access_mode /
backgroud_write_disk_access_mode
* Support for the compressed path would be most beneficial
|OperationType|Writes Data|Direct IO|Reason|
|COMPACTION|Yes|Yes| |
|TOMBSTONE_COMPACTION|Yes|Yes| |
|MAJOR_COMPACTION|Yes|Yes| |
|CLEANUP|Yes|Yes| |
|UPGRADE_SSTABLES|Yes|Yes| |
|GARBAGE_COLLECT|Yes|Yes| |
|ANTICOMPACTION|Yes|Yes| |
|WRITE|Yes|Yes| |
|STREAM|Yes|Yes|Supersedes CASSANDRA-20087|
|SCRUB|Yes|No|Maybe: uses `mark()`/`resetAndTruncate()` for corrupt rollback.
Requires additional plumbing.|
|FLUSH|Yes|No|Excluded: flushed data benefits from page cache due to read
recency|
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