Disk Mirroring Commands

The disk mirror, disk unmirror, and disk remirror commands control disk mirroring. You can issues any of these commands while the devices are in use. In other words, you need not stop databases to set up or modify disk mirroring.

• Initializing Mirrors
  disk mirror starts disk mirroring. Do not use disk init to initialize a mirror device. A database device and its mirror constitute one logical device.
• Unmirroring a Device
  Disk mirroring is automatically deactivated when one of the two physical devices fails.
• Restarting Mirrors
  Use disk remirror to restart a mirror process that has been suspended due to a device failure or with disk unmirror.
• waitfor mirrorexit
  Since disk failure can impair system security, you can include the waitfor mirrorexit command in an application to perform specific tasks when a disk becomes unmirrored.
• Mirroring the Master Device
  If you choose to mirror the device that contains the master database, in a UNIX environment, you must edit the runserver file for your SAP ASE so that the mirror device starts when the server starts.
• Getting Information About Devices and Mirrors
  For a report on all SAP ASE devices on your system (user database devices and their mirrors, as well as dump devices), execute sp_helpdevice.