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

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

Paulo Motta created CASSANDRA-16436:
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             Summary: 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


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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