6947ch08.fm Draft Document for Review April 7, 2004 6:15 pm
216 IBM eServer zSeries 990 Technical Guide
򐂰Changing the number of logical partitions defined to a z990 server.
The only way to add or delete a logical partition is by a POR using a new IOCDS including
or excluding the new partition.
򐂰Changing the number of LCSS on a server.
򐂰Changing the number of subchannels supported on a LCSS.
򐂰Logical partition processor upgrades when reserved processors were not previously
defined are disruptive to image upgrades.
򐂰Memory capacity upgrades are disruptive when memory cards replacement is required.
򐂰Logical partition memory upgrades when reserved storage was not previously defined are
disruptive to image upgrades.
򐂰Installation of I/O cages is disruptive.
򐂰An I/O upgrade when the operating system cannot use the Dynamic I/O configuration
function.
– Linux and CFCC do not support Dynamic I/O configuration.
– If there is no space available in the reserved HSA for the required I/O expansion.
򐂰An STI rebalancing, when the STI Rebalance feature (Feature Code 2400) is ordered at
the server’s upgrade configuration time.
򐂰Adding a PCIXCC or a PCICA coprocessor to a logical partition, if not predefined with the
appropriate PCI cryptographic processor number selected in the PCI Cryptographic
Candidate List of the logical partition’s image profile.
Recommendations to avoid disruptive upgrades
Based on the previous list of reasons for disruptive upgrades, here are some
recommendations to avoid or at least minimize these situations, increasing the possibilities for
nondisruptive upgrades:
򐂰Define spare or reserved logical partitions.
A z990 server can have up to 30 logical partitions defined. It is possible to define more
partitions than you need in the initial configuration, just by:
– including more partition names in the IOCP statement RESOURCE. The spare
partitions do not need to be activated, so any valid partition configuration can be used
during their definitions. The initial definitions (LPAR mode, processors, and so on) can
be changed later to match the image type requirements.
The only resource that spare partitions will use is subchannels, so careful planning
must be done here, keeping in mind that z990s can have up to 1890 K subchannels (63
K per logical partition * 30 partitions) total in HSA.
– defining reserved logical partitions, if you are running z/OS V1.6 or higher. The
dynamic logical partition name definition allows reserved partition ‘slots’ to be created
in an IOCDS in the form of extra logical channel subsystem, Multiple Image Facility
(MIF) image pairs. These extra logical channel subsystem MIF image ID pairs
(CSSID/MIFID) can be later assigned a logical partition name for use (or later
removed) via dynamic I/O commands using the Hardware Configuration Definition
(HCD), concurrently. A reserved partition is defined with the partition name placeholder
‘ * ’, and cannot be assigned to access or candidate list of channel paths or devices.
The IOCDS still must have the extra I/O slots defined in advance, since structures are
built in the Hardware System Area (HSA).
򐂰Define an appropriate number of Logical Channel Subsystems (LCSSs).