Using Operating System Files as Database Devices

For devices that are initialized on operating system files, ensure that device writes occur directly on the physical media.

Use:

directio with disk init and disk reinit
dsync with disk init

directio and dsync parameters are mutually exclusive. If a device has dsync set to true, you cannot set directio to true for this device. To enable directio for a device, also reset dsync to false.

There is no performance difference between dsync and directio on Windows.

The dsync Parameter
The dsync parameter ensures SAP ASE can recover data from devices on file systems.
The directio Parameter
The directio parameter for disk init and disk reinit, lets you bypass the operating system buffer cache and transfer SAP ASE data directly to disk.

Parent topic: SAP ASE Devices and System Databases

Created June 25, 2014. Send feedback on this help topic to Technical Publications: pubs@sap.com