# xSQL Asynchronous I/O

> Asynchronous file I/O can be enabled for optimizing write operations to persistent databases. (Please refer to page Persistent Media I/O for further explanation of AIO).

> ### For an overview see page xSQL Server Instrumentation

> The xSQL configuration file indicates AIO mode in the `db_params` section:

>         db_params : {
>             mode_mask : use_aio,
>         }

> The default size size of the AIO queue is `10007`. This can be modified by setting the value of `aio_queue_length`:

>         db_params : {
>             mode_mask : use_aio,
>             aio_queue_length = 20000,

>         }

> However, since xSQL can only open a single database, the number of AIO worker threads is always one and can't be modified.