User`s guide

364 Implementing an Open IBM SAN

5.10.3 Adding hosts

The SLIC storage system can be expanded to include more hosts whether they

are homogeneous or heterogeneous. It is recommended that as hosts are

added, each host is connected to its own and separate SLIC Router.

If more than one host was connected to a single Router, there will be arbitration

and performance issues. Also, it would have a single point of failure with the

possibility of losing data access to many systems.

Homogeneous hosts

If another host of is added and you would like to have both hosts access the

same disks, then some sort of access sharing software must be loaded onto both

hosts.

If other hosts are added to the storage system and they will not share data, but

are connected for storage consolidation, there are a few issues to be considered

as the Router does not provide a LUN masking capability.

In UNIX systems, the hosts will see all disk in the loop. But, if the specific volume

is not mounted there will be no data integrity problems.

For Windows NT, each host will write its own signature on all available disk.

Adding another Windows NT host to the loop will cause problems. To allow a

specific Router, and host attached to that Router, access to a specific disk or set

of disks, you can set Private Attributes on the disks.

Private Attributes is a setting within SLIC manager that can set a disk to only be

accessed by a certain Router and in turn the host attached to that Router.

In all cases, if extra control for disk access is required, a third party software,

such as Tivoli SANergy, must be used.

Heterogeneous hosts

As the Router does not provide for LUN masking, you must use the SLIC

Manager Private Attribute setting or a third party software, such as Tivoli

SANergy, to restrict and control host access to the disk. The Private Attributes

and Tivoli SANergy can be used together for added control.

Note: For more information and operation on the Private Attributes setting,

please refer to the SLIC Manager Installation and User Guide, 310-605807