Deployment Guide

NOTE: If deploying vSphere hosts, configure only one host at a time.
SAS Virtual Port Mode
To provide redundancy in SAS virtual port mode, the front-end ports on each storage controller must be directly connected to the
server.
In SAS virtual port mode, a volume is active on only one storage controller, but it is visible to both storage controllers. Asymmetric
Logical Unit Access (ALUA) controls the path that a server uses to access a volume.
If a storage controller becomes unavailable, the volume becomes active on the other storage controller. The state of the paths on
the available storage controller are set to Active/Optimized and the state of the paths on the other storage controller are set to
Standby. When the storage controller becomes available again and the ports are rebalanced, the volume moves back to its preferred
storage controller and the ALUA states are updated.
If a SAS path becomes unavailable, the Active/Optimized volumes on that path become active on the other storage controller. The
state of the failed path for those volumes is set to Standby and the state of the active path for those volumes is set to Active/
Optimized.
NOTE: Failover in SAS virtual port mode occurs within a single fault domain. Therefore, a server must have both
connections in the same fault domain. For example, if a server is connected to SAS port 2 on one storage controller, it
must be connected to SAS port two on the other
storage controller. If a server is not cabled correctly when a storage
controller or SAS path becomes unavailable, access to the volume is lost.
Four Servers Connected to Dual 12 Gb 4-Port SAS Storage Controllers
A storage system with four 12 Gb front-end SAS ports on each storage controller can connect to up to four host servers, if each
host server has one HBA with dual SAS ports.
About this task
This configuration includes four fault domains spread across both storage controllers. The storage controllers are connected to each
host server using two SAS connections.
If a storage controller becomes unavailable, all of the standby paths on the other storage controller become active.
Steps
1. Connect fault domain 1 (shown in orange) to host server 1.
a. Connect a SAS cable from storage controller 1: port 1 to the SAS HBA on host server 1.
b. Connect a SAS cable from storage controller 2: port 1 to the SAS HBA on host server 1.
2. Connect fault domain 2 (shown in blue) to host server 2.
a. Connect a SAS cable from storage controller 1: port 2 to the SAS HBA on host server 2.
b. Connect a SAS cable from storage controller 2: port 2 to the SAS HBA on host server 2.
3. Connect fault domain 3 (shown in gray) to host server 3.
a. Connect a SAS cable from storage controller 1: port 3 to the SAS HBA on host server 3.
b. Connect a SAS cable from storage controller 2: port 3 to the SAS HBA on host server 3.
4. Connect fault domain 4 (shown in red) to host server 4.
a. Connect a SAS cable from storage controller 1: port 4 to the SAS HBA on host server 4.
b. Connect a SAS cable from storage controller 2: port 4 to the SAS HBA on host server 4.
52
Connect the Front-End Cabling