Atomic write support for Fusion-io devices


This feature implementation is considered BETA quality.

DirectFS filesystem on Fusion-io devices supports atomic writes. Atomic writes can be used instead of InnoDB doublewrite buffer to guarantee that the InnoDB data pages will be written to disk entirely or not at all. When atomic writes are enabled the device will take care of protecting the data against partial writes. In case the doublewrite buffer is enabled it will be disabled automatically. This will improve the write performance, because data doesn’t need to be written twice anymore, and make the recovery simpler.

Version Specific Information

  • 5.5.31-30.3
    Atomic write support for Fusion-io feature implemented. This feature was ported from MariaDB.

System Variables

variable innodb_use_atomic_writes
Command Line:Yes
Config File:Yes
Variable Type:Boolean
Default Value:0 (OFF)

This variable can be used to enable or disable atomic writes instead of the doublewrite buffer. When this option is enabled (set to 1), doublewrite buffer will be disabled on InnoDB initialization and the file flush method will be set to O_DIRECT if it’s not O_DIRECT or ALL_O_DIRECT already.


innodb_use_atomic_writes should only be enabled on supporting devices, otherwise InnoDB will fail to start.

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