With pre-12.0 versions of Adaptive Server, Sybase recommended that you not place database devices on UNIX operating system files. The integrity of data on such devices could not be ensured, because writes to the file were buffered by the UNIX file system. Adaptive Server could not know when an update was reflected on the physical media, and therefore could not recover databases on the device under certain system failure scenarios. For this reason, UNIX raw partitions were required to ensure the integrity of database devices.
Adaptive Server version 12.0 introduces a new dsync setting for database device files, which controls whether or not writes to those files are buffered. When the dsync setting is on, Adaptive Server opens a database device file using the UNIX dsync flag. The dsync flag ensures that writes to the device file occur directly on the physical storage media, and Adaptive Server can recover data on the device in the event of a system failure.
For more information about the dsync flag, see the Reference Manual entries for disk init, disk reinit, sp_deviceattr, or sp_helpdevice.
