IBM Midrange System DS4000 Series Hardware Manual page 157

Auto-Logical Drive Transfer (ADT) is a built-in feature of controller firmware that allows logical
drive-level failover rather than controller-level failover. Depending on the attached host, the
feature will allow auto-volume transfer based on the characteristics of the operative system
and the driver. You can also enable or disable this feature.
Note: ADT is not a failover driver. ADT provides storage systems with the flexibility to work
with some third-party failover software.
The two modes are:
ADT-disabled failover
The multi-path software will send a SCSI Mode Select command to cause a change in
volume ownership before using the alternate path. All logical drives on the preferred
controller are transferred to the alternate controller. This is the configuration setting for
Microsoft Windows, IBM AIX, and Linux (when using the RDAC or SDD driver and
non-failover Fibre Channel HBA driver) systems. When ADT is disabled, the I/O data path
is still protected as long as you use a multi-path driver. After the I/O data path problem is
corrected, the preferred controller does not automatically reestablish ownership of the
logical drive. You must open a storage management window, select Redistribute Logical
Drives from the Advanced menu, and perform the Redistribute Logical Drives task.
Chapter 4. IBM System Storage DS planning and configuration
139