A partition chassis (“chassis,” for short) is a logical container representing the location into which the partition’s software (that is, the gold image) is to be loaded. A 4-socket, 15-cores per socket enterprise partition platform (EPP) includes up to 30 partition chassis; other types of EPPs include an equal number or less. There is one and only one enabled chassis per partition.
Chassis are named Chassis A, Chassis B, Chassis C, and so forth. During commissioning, you use the Fabric Manager user interface to select the chassis for the partition image.
Chassis Rules
There is one and only one enabled chassis per partition.
There is a relationship between the partition chassis and the number of processor cores that a partition commissioned using that chassis may include:
Chassis A always supports the maximum number of cores allowed for that EPP type.
In general, the higher you go in the alphabet (that is, toward Chassis Z), the fewer the number of processor cores that may be included in the partition.
Therefore
If you want one or more large partitions, commission using chassis low in the alphabet, for example, Chassis A, Chassis B, and so on.
If you want many small partitions, you have great freedom in which chassis you choose.
Multiple partition images can share the same chassis, as long as only one of the partition images is enabled at a time.
Partition images are automatically enabled after commissioning. But using the Fabric Manager, you can disable them. Disabling all partition images that share the same chassis except one allows you to commission multiple partition images that use the same chassis. (Disabling a partition image frees up its hardware resource blocks; however the partition image content is persisted on mass storage for possible future use. That means you can enable the partition image later.)