Note
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.
- 5.6.11-60.3
Atomic write support for Fusion-io feature implemented. This feature was ported from MariaDB.
| Command Line: | Yes |
|---|---|
| Config File: | Yes |
| Scope: | Global |
| Dynamic: | No |
| 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 O_DIRECT_NO_FSYNC already.
Warning
innodb_use_atomic_writes should only be enabled on supporting devices, otherwise InnoDB will fail to start.
- For general InnoDB tuning Improved InnoDB I/O Scalability documentation is available.
- FusionIO DirectFS atomic write support in *MariaDB*
- Atomic Writes Accelerate MySQL Performance
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