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About The Shared PERC 8 Card
The Dell Shared PowerEdge RAID Controller (PERC) 8 card installed on the Dell PowerEdge VRTX system
supports Single Root Input Output Virtualization (SR-IOV). This feature allows multiple systems to share
available hardware resources.
The PERC 8 card allows four server modules to access a local shared storage. Each server module's
operating system loads a Virtual Function (VF) driver that allows the server module to communicate with
the Shared PERC 8 firmware. The server module can then be mapped to either a single virtual disk or
multiple virtual disks that are located on the shared storage. From a single server module, you can only
access the virtual disks that are mapped to that server module.
Configurations of the Shared PERC 8 card
The PowerEdge VRTX system is available in two configurations of the Shared PERC 8 card:
Single Shared PERC 8 Card Configuration — In this configuration, the PowerEdge VRTX system is installed
with a single Shared PERC 8 card. The default cache policy for virtual disks created in this configuration is
write-back. In this mode, write completion information is returned to the host after the data is written to
the Shared PERC 8 controller’s cache.
Fault Tolerant Shared PERC 8 Card Configuration — In this configuration, the PowerEdge VRTX system is
installed with two Shared PERC 8 cards. The shared PERC cards are configured in an active-passive
mode. Both the cards can access the storage subsystem. However, only the active controller will provide
the data access. If one Shared PERC 8 card fails, the other Shared PERC 8 card takes control in a
seamless transition.
Checkpoints are created for all background operations. After a failover, operations are restored from the
last checkpoint. The default cache policy for virtual disks created in this configuration is write-back. In
this mode, write completion information is returned to the host after the data is written to the peer
shared PERC 8 controller’s cache.
Host data is also mirrored to the peer controller's cache to allow seamless operation in case of a primary
card failure.
Important information regarding the Fault Tolerant Shared PERC 8 Card Configuration:
• Multipath support must be enabled in the operating system for the Fault Tolerant Shared PERC 8 card
configuration to function.
• In the event of a controller failover, a Background Initialization (BGI) starts automatically on each
virtual disk.
• An ongoing full initialization does not restart in the event of a failover.
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