Administrator Guide

The Storage Center Settings dialog box opens.
4. Click the Users and User Groups tab.
5. On the Directory User Groups subtab, select the directory user group, then click Delete.
The Delete dialog box opens.
6. Click OK to confirm.
7. Click OK.
Managing Front-End I/O Ports
Fibre Channel (FC), iSCSI, and SAS ports on a storage system may be designated for use as front-end I/O ports. Front-end
I/O ports can connect to Fibre Channel fabrics or Ethernet networks that contain servers that require storage, or directly to a
server using SAS connections.
Front-End Connectivity Modes
Storage Center uses either legacy mode, virtual port mode, or ALUA port mode to transport data to servers that use SAN
storage. In legacy mode, front-end I/O ports are configured in pairs of primary and reserved ports. In virtual port mode, all ports
are active, and if one port fails the load is distributed between the remaining ports within the same fault domain. In ALUA port
mode, volumes are mapped using two paths, active and passive.
NOTE: In Legacy mode, reserve ports and primary ports reside on separate controllers, providing controller-level failover
only. Legacy mode does not provide port-level failover.
The front-end connectivity mode is configured independently for Fibre Channel and iSCSI. Both transport types can be
configured to use the same mode or different modes to meet the needs of the network infrastructure. For example, a Storage
Center can be configured to use virtual port mode for iSCSI and legacy mode for FC.
● The front-end connectivity mode for FC and iSCSI ports is initially selected during Storage Center deployment.
● After deployment, the front-end FC and iSCSI ports can be changed from legacy mode to virtual port mode.
○ After FC and iSCSI ports are configured for virtual port mode, they cannot be changed back to legacy mode.
NOTE: Use legacy port mode only if the network environment does not meet the requirements for virtual port mode.
● The front-end connectivity mode for SAS front-end is always ALUA port mode and cannot be changed.
Virtual Port Mode
Virtual port mode provides port and controller redundancy by connecting multiple active ports to each Fibre Channel or Ethernet
switch.
In virtual port mode, each physical port has a WWN (World Wide Name), and is also assigned an additional virtual WWN. Servers
target only the virtual WWNs. During normal conditions, all ports process I/O. In the event of a port or controller failure, a virtual
WWN will move to another physical WWN in the same fault domain. When the failure is resolved and ports are rebalanced, the
virtual port returns to the preferred physical port.
Virtual port mode provides the following advantages over legacy mode:
● Increased performance: Because all ports are active, additional front-end bandwidth is available without sacrificing
redundancy.
● Improved redundancy: Ports can fail over individually instead of by controller.
● Simplified iSCSI configuration: Each fault domain has an iSCSI control port that coordinates discovery of the iSCSI ports
in the domain. When a server targets the iSCSI port IP address, it automatically discovers all ports in the fault domain.
ALUA Port Mode
Asymmetric Logical Unit Access (ALUA) provides port and controller redundancy for SAS front-end connections.
Volumes mapped to a server using SAS front-end also have port and controller redundancy. Volumes mapped over SAS are
mapped to both controllers. The volume mapping is Active/Optimized on one controller and Standby on the other controller. If
the port or controller fails on the active controller, the paths to the other controller become Active/Optimized. The mapping
on the first controller switches to Standby. When the port or controller recovers, the mapping to the first controller returns to
Active/Optimized and the mapping to the second controller returns to Standby status.
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Storage Center Maintenance