Administrator Guide

• For SCv3000 series storage systems with SAS HBAs, four fault domains are created for the SAS ports.
• For SCv3000 series storage systems with iSCSI mezzanine cards, two fault domains are created for the iSCSI ports.
• For SCv3000 series storage systems with iSCSI mezzanine cards and iSCSI HBAs, four fault domains are created for iSCSI ports
NOTE: Additional front-end fault domains cannot be created on SCv3000 series storage systems. In addition, existing fault
domains cannot be modied or deleted on SCv3000 series storage systems.
Fault Domains for Front-End SAS Ports for SC4020 Storage Systems
Users can select the number of fault domains to create for front-end SAS ports on SC4020 Storage Systems.
Fault domain behavior on SC4020 Storage Systems:
• Storage Center generates the SAS fault domains by pairing un-used front-end SAS ports into fault domains. If all SAS front-end ports
are already included in fault domains, fault domains cannot be created.
– Storage Center uses one port from each controller.
– The paired ports have the same port number.
• Users can modify fault domain names and notes about the fault domain.
• Users can delete SAS fault domains.
• Users cannot add, move or remove ports within SAS fault domains.
Fault Domains in Virtual Port Mode
In virtual port mode, fault domains group front-end ports that are connected to the same Fibre Channel fabric or Ethernet network. All
ports in a fault domain are available for I/O. If a port fails, I/O is routed to another port in the fault domain.
The following requirements apply to fault domains in virtual port mode:
• Fault domains are created for each front-end Fibre Channel fabric or Ethernet network.
• A fault domain must contain a single type of transport media (FC or iSCSI, but not both).
CAUTION
: For iSCSI only, servers initiate I/O to iSCSI ports through the control port of the fault domain. If an iSCSI port
moves to a dierent fault domain, its control port changes. This change disrupts any service initiated through the previous
control port. If an iSCSI port moves to a dierent fault domain, you must recongure the server-side iSCSI initiators before
service can be resumed.
• For each fault domain, it is a best practice to connect at least two cables from each controller to the Fibre Channel fabric or Ethernet
network.
Fault Domains in Legacy Mode
In Legacy Mode, each pair of primary and reserved ports are grouped into a fault domain. The fault domain determines which ports are
allowed to fail over to each other.
The following requirements apply to fault domains in legacy mode on a dual-controller Storage Center:
• A fault domain must contain one type of transport media (FC or iSCSI, but not both).
• A fault domain must contain one primary port and one reserved port.
• The reserved port must be located on a dierent controller than the primary port.
NOTE
: For a single-controller Storage Center, only one fault domain is required for each transport type (FC or iSCSI) because
there are no reserved ports.
Storage Center Maintenance 265