innodb_flush_method variable specifies how InnoDB opens and flushes log and data files. In Innodb optimization, setting the variable innodb_flush_method tweaks the performance most of the times but there are cases...

We want to use large transaction log files for InnoDB to reduce page writes done for fuzzy checkpoints. The sum of the sizes for log files is 4G in official MySQL and much larger in Percona XtraDB. I previously published results to show the benefit from using larger log files. Until recently we were concerned about that impact of log files on crash recovery time. Crash recovery is much faster now. We are also concerned about the impact on the buffer pool. We run with innodb_flush_method=O_DIRECT. When this is set log files use buffered IO and can use space in the OS buffer cache. We prefer not to dedicate 4G or more of RAM for caching log files.

 

The alternative on Linux is to use O_DIRECT for log

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