Usage information for dsync.
When dsync is on, writes to the database device are guaranteed to take place on the physical storage media, and the SAP ASE server can recover data on the device in the event of a system failure.
directio and dsync 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, you must first reset dsync to false.
When dsync is off, writes to the database device may be buffered by the UNIX file system. The UNIX file system may mark an update as being completed, even though the physical media has not yet been modified. In the event of a system failure, there is no guarantee that data updates have ever taken place on the physical media, and the SAP ASE server may be unable to recover the database.
dsync is always on for the master device file.
Turn off the dsync value only when databases on the device need not be recovered after a system failure. For example, you may consider turning dsync off for a device that stores only the tempdb database.
The SAP ASE server ignores the dsync setting for devices stored on raw partitions—writes to those device are guaranteed to take place on the physical storage media, regardless of the dsync setting.
The dsync setting is not used on the Windows NT platform.
disk reinit ensures that master..sysdevices is correct if the master database has been damaged or if devices have been added since the last dump of master.