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https://issues.apache.org/jira/browse/CASSANDRA-21134?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sam Lightfoot updated CASSANDRA-21134:
--------------------------------------
Description:
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|
was:
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|
> Direct IO support for background writes
> ---------------------------------------
>
> Key: CASSANDRA-21134
> URL: https://issues.apache.org/jira/browse/CASSANDRA-21134
> Project: Apache Cassandra
> Issue Type: Improvement
> Components: Local/SSTable
> Reporter: Sam Lightfoot
> Assignee: Sam Lightfoot
> Priority: Normal
> Fix For: 6.x
>
> Attachments: image-2026-02-11-17-22-58-361.png,
> image-2026-02-11-17-25-58-329.png, image-2026-03-06-22-05-34-147.png,
> image-2026-03-07-10-47-44-878.png
>
>
> 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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