The Shared PERC 8 Internal and External cards are two separate SAS
domains. The PowerEdge VRTX system is available in the following configurations
for both Internal and External cards:
Single
Non-Fault Shared PERC 8 Card Configuration
— In this configuration,
the controllers do not mirror their cache. The default cache policy
for virtual disks created in this configuration is write-back. In
this mode, the write completion information is returned to the host
after the data is written to the Shared PERC 8 controller’s cache.
Dual Fault Tolerant Shared PERC 8 Card Configuration — In this configuration, there are two Shared PERC 8 cards configured
in an active-passive cluster. Both controllers can access the same
storage subsystem. However, only the active controller provides the
data access. If one of the Shared PERC 8 cards fails, the other Shared
PERC 8 card takes control in a seamless transition. The default cache
policy for virtual disks created in this configuration is write-back.
-
NOTE: For Shared PERC 8 External controllers, the Fault Tolerance option must
be set by the user and the required cabling topology must be used.
The following configuration is only available for
External cards:
Dual Non-Fault Tolerant Shared
PERC 8 External Cards Configuration
— In this configuration, the
PowerEdge VRTX system contains two Shared PERC 8 External cards where
both are cabled to separate JBODs creating separate SAS domains. If
one Shared PERC 8 External card fails, access to the storage subsystem
attached to that card is lost. This configuration option is not available
for Shared PERC 8 Internal cards.