Product manual

Managing Critical Data
77 A1 69UP Rev00 5-9
In summary, dual-initiator provides the following advantages:
• Ensures continuous data availability if a CDA 7 disk management component
fails
• Provides continuous operation by switching data pathing to the alternate disk
director without interruption when a communications failure occurs with one or
more disk devices
• Re-establishes normal data pathing after repair of the defective component
Dual-initiator provides an additional level of data availability in mirrored
configurations. If CDA 7 is unable to read from or write to one of the devices in a
mirrored pair, CDA 7 automatically uses the other disk device in the pair without
interruption. If CDA 7 fails to communicate with that device also, CDA 7 then
attempts to access the volume through the alternate path provided by the dual-
initiator function.
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5.2.5 Non-disruptive Component Replacement
CDA 7, with its redundant architecture, supports non-disruptive replacement of
many of its components. This includes online replacement of the directors
(channel directors and disk directors), memory cards, disk devices, adapters
(dual-initiator, serial), power supplies, communications cards, and cooling fans.
This non-disruptive replacement capability allows the Bull Customer Engineer to
install a new component, initialize it if necessary, and bring it online without:
• Disrupting access to unaffected volumes
• Powering down the CDA 7 unit
• Stopping the operating system
• Taking unaffected channel paths offline
• Taking devices offline (other than the affected device)
This replacement must be done under controlled conditions, please contact your
Bull Competence Center. For a demonstration of non-disruptive component
replacement, contact your Bull Customer Service representative.
NOTE:
When replacing a Director, all activity on the director must be stopped before
attempting this operation.