Skip to content

Improved InnoDB I/O scalability

Because InnoDB is a complex storage engine it must be configured properly in order to perform at its best. Some points are not configurable in standard InnoDB. The goal of this feature is to provide a more exhaustive set of options for XtraDB.

Version specific information

  • 8.0.12-1: The feature was ported from Percona Server for MySQL 5.7.


Implemented in Percona Server for MySQL 8.0.13-4, max checkpoint age has been removed because the information is identical to log capacity.

System variables


Option Description
Command-line Yes
Config file Yes
Scope Global
Dynamic No
Data type Enumeration
Default NULL
Allowed values fsync, O_DSYNC, O_DIRECT, O_DIRECT_NO_FSYNC, littlesync, nosync

The following values are allowed:

* `fdatasync`: use `fsync()` to flush data, log, and parallel doublewrite files.

* `O_SYNC`: use `O_SYNC` to open and flush the log and parallel doublewrite files; use `fsync()` to flush the data files. Do not use `fsync()` to flush the parallel doublewrite file.

* `O_DIRECT`: use O_DIRECT to open the data files and `fsync()` system call to flush data, log, and parallel doublewrite files.

* `O_DIRECT_NO_FSYNC`: use O_DIRECT to open the data files and parallel doublewrite files, but does not use the `fsync()` system call to flush the data files, log files, and parallel doublewrite files. Do not use this option for the *XFS* file system.


On an ext4 filesystem, set innodb_log_write_ahead_size to match the filesystem’s write-ahead block size. This variable avoids unaligned AIO/DIO warnings.

Starting from Percona Server for MySQL 8.0.20-11, the innodb_flush_method affects doublewrite buffers exactly the same as in MySQL 8.0.20.

Status variables

The following information has been added to SHOW ENGINE INNODB STATUS to confirm the checkpointing activity:

The max checkpoint age
The current checkpoint age target
The current age of the oldest page modification which has not been flushed to disk yet.
The current age of the last checkpoint
Log sequence number 0 1059494372
Log flushed up to   0 1059494372
Last checkpoint at  0 1055251010
Max checkpoint age  162361775
Checkpoint age target 104630090
Modified age        4092465
Checkpoint age      4243362
0 pending log writes, 0 pending chkp writes

Get expert help

If you need assistance, visit the community forum for comprehensive and free database knowledge, or contact our Percona Database Experts for professional support and services.

Last update: 2023-09-27