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DuraStor 412R/6320SS/7320SS Installation and User’s Guide
Arrays can only be accessed by the controller that currently owns
them. One controller will have no visibility to the others’ arrays. If
one controller fails, the surviving controller will take ownership of
all arrays. Pool spares and unassigned disks are visible to both
controllers.
The two controllers communicate via the back-end disk buses.
Although many different message types are sent between the two
controllers, the majority of the data is write cache data. In the
default write-back caching mode, any data that the host writes to
one controller is copied to the other controller before a good status
is returned to the host. By mirroring the data, if a controller fails,
the surviving controller will have a copy of all data that has not
been written to the disk.
Warning:
The controllers communicate with each other using
SCSI Initiator IDs 6 and 7 on each of the disk channels. You
should not change these ID settings.
Each controller sends heartbeat messages to its partner controller.
If a controller does not receive a heartbeat message within a set
time period, it will kill the other controller assuming that it has
malfunctioned.
After killing the other controller, it will take ownership of the
arrays and will activate its passive host port to assume the defunct
controller’s identity.
DuraStor IUG - Online.book Page 8 Friday, July 19, 2002 3:06 PM
