Understanding Operating Modes; Understanding The Active-Active Configuration - Adaptec DuraStor 7220SS User Manual

Understanding Operating Modes

Your controller can operate in three different modes:
Active-active—Two controllers cooperate in system operation
I
in a fault-tolerant manner. If one controller fails, the other takes
over the failed controller's work, providing another level of
redundancy and allowing host access to continue.
Stand-alone dual-port—A single controller operating with two
I
host ports. This mode allows the host to achieve greater
throughput by balancing I/O operations across the two host
ports. Host port fault tolerance is also achieved, because the host
can continue to access the controller if one host channel fails.
The same LUNs display on the two separate host ports.
Caution: The host OS and disk drivers must support dual-
!
port accesses for this mode to be used effectively. If the
host system does not support dual-port access, do not
configure the controller in dual-port mode—the OS may
believe that a single LUN is really two independent arrays,
which may result in data corruption.
Stand-alone single-port—A single controller operating with
I
one host port and three disk channels. Use this mode if you do
not want to run in dual-port mode, or if your host OS does not
support it.
Note: If you select stand-alone single-port mode, SCSI
channel 3 will not be available if it has been disabled in the
Flash Utility. See
Disabling SCSI channel 3 forces the controller into stand-
alone single-port mode.

Understanding the Active-Active Configuration

Below are terms associated with active-active configurations, as
they apply to the DuraStor Storage Subsystem:
Controller 1 and 2—One controller is designated as the
I
Controller 1 and the other controller is designated as Controller
2. The controller's identity appears continuously at the bottom
Disabling SCSI Channel 3 on page
Configuring the Controller
5-14.
5-8