Disk Mirroring

Disk mirroring creates a software mirror that immediately takes over when the primary device fails.

At the beginning of a load, the SAP ASE server passes the primary device name of each logical database device and each logical log device to the Backup Server. If the primary device has been unmirrored, the SAP ASE server passes the name of the secondary device instead. If any named device fails before the Backup Server completes its data transfer, the SAP ASE server aborts the load.

If you attempt to unmirror any of the named devices while a load transaction is in progress, the SAP ASE server displays a message. The user executing disk unmirror can abort the load, or defer disk unmirror until after the load completes.
Backup Server loads the data onto the primary device, then load transaction copies it to the secondary device. load transaction takes longer to complete if any database device is mirrored.