Chapter 8. Capacity upgrades 217
Draft Document for Review April 7, 2004 6:15 pm 6947ch08.fm
Define the appropriate number of LCSSs (maximum is 4), 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 to spread logical partitions across LCSSs while maintaining
physical channels sharing for some channel types (see Table3-8 on page 91 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.

Considerations when installing additional books

During a z990 server upgrade, additional books can be concurrently installed. Depending on
the number of additional books in the upgrade and the customer’s I/O configuration, an STI
Rebalancing may be recommended for availability reasons. However the z990 STI
Rebalancing, via the STI Rebalance feature, requires STI recabling and results in a server
outage. It may also change ICB-4 PCHID numbers, requiring an I/O definition update.
8.7 Capacity planning considerations
The z990 servers represent a major evolution for the Series platform, extending the key
platform characteristics and embracing e-business on demand requirements.
The z990 has significant performance improvements over the previous z900 servers. The
z990 server includes enhanced processor and system designs, and also introduces new
building blocks, such as the multi-book structure.