Logical partition concept: Bus-level and IOP-level I/O partitions

Depending on your needs, there can be advantages to setting up one type of I/O partition instead of another.

With bus level I/O partitions, the system partitions I/O resources by bus. On a server that is completely partitioned at the bus level, every secondary partition has its own removable media and workstation.

Bus-level logical partitions allow for:

• Better problem isolation and therefore higher availability.
• Better performance.
• Simplified hardware management.

When you partition a server at the IOP level, one or more buses are shared and divided up between the I/O resources by the IOP. This type of logical partitions allows for:

• Greater flexibility when partitioning I/O subsystem.
• Potential cost reduction by eliminating some expansion units which the server requires to support additional buses.
• Optimization of hardware resources to avoid server limits.
• The ability to dynamically move the control of an IOP from one partition to another without the need to restart the system.
• Simplified configuration planning since you can dynamically move hardware from one partition to another.

You might also consider having a system configuration with both bus-level partitioning and IOP-level partitioning. For example, you may put all of the IOPs that you wish to switch in a shared bus and configure all other logical partitions to have bus-level partitioning. The shared bus can then belong to a test partition. This allows you the ability to switch IOPs such as tape drives or LAN adapters to partitions that need these resources.