User`s guide

Chapter 5. Implementing the Vicom Fibre Channel SLIC Router 361
5.10 Expanding the SLIC system
The SLIC storage system can be expanded to add more SSA disks or more SLIC
Routers. Each SLIC storage system can support up to 64 SSA disks and have 16
Routers.
5.10.1 Adding disk
To add disk to an existing SLIC system is very easy, because they are SSA disks
and the rules for SSA disks apply here as well.
If there is a dummy drive in an existing SSA drawer, then it can be replaced by a
real drive. If a new drawer has to be added, the SSA cabling is changed to
include this new drawer.
Because this is SSA, this can be done on the fly. As the SSA loop is broken, the
Router will still access all disks due to the structure of the SSA loop. If possible,
we recommended that you stop host access and power down the loop. In any
case, the rules regarding SSA disks and cabling must be adhered.
As disks are added to an existing loop, the new disks will be recognized. If all
disks in the loop are used as single disks (JBOD) and have LUN numbers
assigned, the new disks added will have LUN numbers assigned to them
automatically. If there are any composite, mirror, instant copy, or spare drives in
the loop, then the new disks will not have LUN numbers assigned and become
general spares.
5.10.2 Adding Routers
By adding Routers we can increase the amount of storage a host can access and
increase throughput. On the rear panel of the Router, there are two Fibre
Channel GBIC ports that are available and act as a mini-hub.
You can add a Fibre Channel cable from the second port on the existing Router
to one of the ports on the second Router. You are basically daisy-chaining the
Routers. But since the ports on the Router act as a hub, an arbitrated loop is
created. However, in this scenario there is only one Fibre Channel cable from the
host to the Router and it is a single point of failure.
Another option is to add a second Fibre Channel host adapter that will connect to
the other Router. This provides a high availability feature, because there are now
two paths to the storage system. Software must be used for automatic failover
and load balancing between the two Fibre Channel host adapters. Failover also
can be done manually if so desired.