MIF and multiple LCSSs

Published 21 May 2003, updated 09 December 2004

Authors: Bill White


The structure of the multiple LCSS is an extension to that provided with previous z/Architecture servers. It provides channel connectivity to the defined logical partitions in a manner that is transparent to subsystems and application programs.
The multiple LCSS introduces new components and terminology that differs from previous server generations. These components are explained in this Technote.


With the introduction of multiple LCSSs, the logical partition number is no longer specified in the HCD/IOCP. With the introduction of multiple LCSSs, the IOCDS logical partition MIF Image ID is no longer unique within the z990 and z890 servers. Therefore, the logical partition identifier value has been changed to provide a unique value for each logical partition within the same server. The following terminology applies:

Logical partition number

This number cannot be specified by the user for the z990 or for the z890; actually, it is not even visible to the user. The concept of logical partition number has been replaced by MIF ID.

Logical partition name

The logical partition name is defined by the user through HCD or IOCP. It’s the name in the RESOURCE statement in the IOCP. The logical partition names must be unique across all LCSSs.

Logical partition identifier

The logical partition identifier is a number in the range of 00 to 3F and is assigned in the image profile through the Support Element (SE) or the Hardware Management Console (HMC). It is unique across the server (z990 or z890) and may also be referred to as the User Logical Partition ID (UPID).

We suggest you establish a numbering convention for the logical partition identifiers. As shown in the diagram below, you could use the LCSS number concatenated to the MIF Image ID, which means logical partition ID 3A is in LCSS 3 with MIF ID A. This fits within the allowed range of logical partition IDs and conveys useful information to the user.


This identifier is defined through the Hardware Configuration Definitions (HCD) or via IOCP. This is the number defined in the RESOURCE statement in the IOCP. It is in the range of 1 to F and is unique within a LCSS. It is not unique across multiple LCSSs within the z990 or z890. Multiple LCSS may specify the same MIF ID (also known as Image ID (IID)).

The following diagram summarizes all the identifiers and how they are defined using a four LCSS configuration example.

Special Notices

This material has not been submitted to any formal IBM test and is published AS IS. It has not been the subject of rigorous review. IBM assumes no responsibility for its accuracy or completeness. The use of this information or the implementation of any of these techniques is a client responsibility and depends upon the client's ability to evaluate and integrate them into the client's operational environment.

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