[jira] [Commented] (CASSANDRA-16436) Add startup check for large read_ahead_kb setting

["Paulo Motta (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-16436?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17467659#comment-17467659 ] 

Paulo Motta commented on CASSANDRA-16436:
-----------------------------------------

Set ticket status back to open. Please set back to Patch Available after PR review is addressed.

> Add startup check for large read_ahead_kb setting
> -------------------------------------------------
>
>                 Key: CASSANDRA-16436
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-16436
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Local/Startup and Shutdown
>            Reporter: Paulo Motta
>            Assignee: Kanthi Subramanian
>            Priority: Normal
>              Labels: AdventCalendar2021, lhf
>
> A well known production tuning recommendation is to dial back the {{read_ahead_kb}} Linux setting from the default of 4096 in most distributions as this can cause high IO usage and cache churn on read-intensive workloads.
> We should add a startup warning to detect when a high {{read_ahead_kb}} is used and recommend the user to dial back to a reasonable value, which varies according to the workload but a general guideline is to tune this to 8kb.



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