6947ch08.fm Draft Document for Review April 7, 2004 6:15 pm
212 IBM eServer zSeries 990 Technical Guide
At this point, even with no partition configuration changes, LP2 and LP3 (shared) partitions
may experience performance improvements. As there is now more available capacity
(physical processors) to be used by all logical shared CPs, the “logical-to-physical processors
ratio” is reduced. In this example, before the upgrade, there were twelve shared logical CPs
(six for LP2 and six for LP3) to be dispatched into six physical CPs. If all twelve logical CPs
have tasks to run, six of them have to wait. After the physical upgrade, up to seven shared
logical CPs can run at the same time.
Now let’s consider the logical upgrades, assuming that all operating systems running in these
partitions have the capability of configuring processors online. Partition LP1, which has two
reserved CPs defined, can configure up to two more CPs online. In this example, LP1 is
configuring one more CP online, remaining with one reserved CP for a future image upgrade.
LP1 now has four dedicated CPs, enabled by doing a nondisruptive upgrade.
From the eleven physical CPs available, seven CPs are left to be shared by LP2 and LP3
shared logical CPs.
򐂰LP2 has six logical CPs and two reserved CPs defined, but only one more can be
configured online, as the current configuration has only seven CPs to be shared. After the
LP2 logical upgrade, one reserved CP remains offline.
򐂰LP3 has the same configuration as LP2, and in this example it is not being changed.
However, it could have one more reserved CP configured online.
򐂰LP1 and LP2 remain with one reserved CP each, but they cannot be configured online in
the current configuration. However, if LP1 configures one dedicated CP offline, then LP2
can activate its last reserved CP.
Shared partitions and zAAP upgrade
Figure 8-13 on page 213 is an example of a nondisruptive upgrade, adding three zSeries
Application Assist Processors (zAAPs) to a 2084-B16, software model 309 server.