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DuraStor 412R/6320SS/7320SS Installation and User’s Guide
In the failed-over condition, the active controller will present its
native identity on one FC host port, and the failed-over controller’s
identity on the other port. This is slightly different when using a
dual port configuration, where each array is presented on both FC
host ports.
After the controller has failed-over, the user can replace the failed
controller with a new controller, and the arrays will fail-back to the
new controller without intervention. If you want to retry the failed
controller, it’s necessary to release the kill line that the survivor
asserts. This is accomplished using Storage Manager Pro or the
Disk Array Administrator (Other Controller Menu, Unkill Other
option).
If you replace a failed controller with a new controller, the new
controller will attempt to retrieve its configuration (see
Understanding Mirrored Operations
) from the
surviving controller. This means that the replacement controller
will boot up with the same configuration as the controller it
replaced.
If the surviving controller for some reason does not contain a valid
mirrored configuration, you must manually configure the
replacement controller. The correct host target ID must be set, and
the active-active operating mode must be enabled.
The Active-Active controller system makes some assumptions
about the host operating system’s SCSI processing. The host must
retry incomplete commands after a specific time period. This retry
is necessary because a host may issue a command to a controller,
the controller fails over, and the new controller does not have a
copy of the command.
Advantages
■
LUN isolation with the single-port, single host system.
■
Dedicated LUNs with a single-port, dual host system.
■
Access to all LUNs with a dual port-dual host quad cabling
configuration.
■
Provides transparent fail-over and fail-back.
■
No single point of failure with the active-active dual-port
configuration, must have third-party clustering and file share/
file lock software installed.
DuraStor IUG - Online.book Page 20 Friday, July 19, 2002 3:06 PM