nStor NexStor 4200F Series, User Manual

Page: 47 / 174

Chapter 2 - Topologies and Operating Modes
Understanding Mirrored Configurations
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Understanding Mirrored Configurations
The mirroring feature causes controller configuration changes to be mirrored to
the opposite controller in an duplex operating mode. The mirrored configuration
is stored in the other controller’s onboard memory. If a controller fails and is
replaced, then on boot up, it attempts to retrieve this configuration data from the
opposite controller. The intent is that the user will not need to reconfigure a new
controller when it is replaced.
CAUTION:
Active-Active RAID controller operations require that both controllers
have the same version firmware and the same amount of memory
installed.
If a replacement controller uses its mirrored configuration, you will see it print a
message during boot (saying it’s using the mirrored configuration), and then it
will reboot (rebooting is necessary for the mirrored configuration to take effect).
Here’s how the mirrored configuration works in different scenarios:
■
Simplex mode – This feature is not active.
■
Duplex mode where both controllers are operating normally – Each
controller uses its own local configuration.
■
Duplex mode where one controller boots and the other controller does not
boot due to some problem – The controller that boots uses its local
configuration.
■
Duplex mode where one controller is up when a new replacement
controller boots – the new controller attempts to get its mirrored
configuration from the other controller. If it is not available, it will try to
use its local configuration. If that is not available, then it will use the
default settings.
4200F.book Page 35 Thursday, January 23, 2003 2:47 PM