3-51
Installing the DuraStor Storage Subsystem
Hubs Disabled (Single-Port Hosts and One Switch)
In
Figure 3-46
, two single-ported hosts connected to the DuraStor
7220SS storage subsystem’s two controllers via a single switch. In
this case, there would be an advantage to configuring the
controllers in active-active dual-port mode, because of increased
connectivity. However, the host driver software would need to
handle the fact that each LUN would appear twice in the SAN
fabric, and that one image of the LUNs would disappear if one
controller failed. Depending on the host software being used, it
may be more desirable to run in active-active single-port mode,
since a controller failover would be transparent to the hosts (as far
as the number of LUN images and the port WWNs attached to the
LUNs). The advantages of using a switch is that the two hosts each
have a direct path to a controller port and don’t have to compete
for access on the same loop.
Figure 3-46 Active-Active Single-Port Hubs Disabled
Host 2
FC HBA
Host 1
Switch
FC HBA
Host Link 1
Host Link 2
Up to 12 Disk Drives
Up to 12 Disk Drives
Up to 12 Disk Drives
Up to 12 Disk Drives
P2
FC2
FC1
FC2
FC1
Controller 2
DuraStor FC RAID Appliance
Controller 1
CH0
CH0
CH1
CH1
CH2
CH2
CH3
CH3
CH0
CH1
CH2
CH3
P1
P3
P4
LUN 2
Active
LUN 2
Passive
LUN 1
Active
LUN 1
Passive
T
T
T
T
DuraStor IUG.book Page 51 Wednesday, January 30, 2002 10:49 AM
