IBM 990 - Manual (Page 230)

218 IBM
^
zSeries 990 Technical Guide
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 our 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).
Define the appropriate number of LCSSs (maximum is four), based on the required
number of logical partitions (maximum is 30) and the number of CHPIDs (maximum is 256
per image and per LCSS) that a future configuration may have. Spare and reserved
logical partitions, which can have partition name ‘
* ‘ for future renaming, as described in
the previous item, can help to define additional LCSSs for future use.
Spanned channels can help spread logical partitions across LCSSs while maintaining
physical channels sharing for some channel types (see Table 3-8 on page 92 for a list of
supported spanned channels).
Define the maximum supported number of subchannels on each LCSS.
The z990s can have up to 1890 K subchannels (63 K per logical partition * 30 partitions)
total in HSA (the current maximum number of subchannels on a
z900 is 63 K).
Configure as many Reserved Processors (CPs, IFLs, ICFs, and zAAPs) as possible.
Configuring Reserved Processors for all logical partitions before their activation enables
them to be nondisruptively upgraded. The operating system running in the logical partition
must have the ability to configure processors online.
Configure Reserved Storage to logical partitions.
Configuring Reserved Storage for all logical partitions before their activation enables them
to be nondisruptively upgraded. The operating system running in the logical partition must
have the ability to configure memory online. The amount of reserved storage can be
above the book threshold limit (64 GB), even if no other book is already installed. The
current partition storage limit is 128 GB.
Start with a convenient memory size.
Use a convenient entry point memory capacity to allow future concurrent memory
upgrades within the same memory cards already installed on the books.
Use the Plan Ahead concurrent condition for I/O.
Use the Plan Ahead concurrent condition process to include in the initial configuration all
the I/O cage(s) required by future I/O upgrades, allowing the planned concurrent I/O
upgrades.
Define all possible PCI cryptographic coprocessors as candidates for all logical partitions.
You can select PCI cryptographic processor numbers in the PCI Cryptographic Candidate
List of an image profile even if there are no PCIXCC or PCICA coprocessors currently
installed on the server.