IBM 990 - Manual (Page 93)

Chapter 3. I/O system structure 81
Figure 3-5 2084-B16-to-D32 upgrade example
This upgrade adds, concurrently, two more books in the CEC cage, and the standard upgrade
configuration will
not change the STI links’ original distribution and connections. The new
books 2 and 3 do not have any STI connection and all STI links remain in the original books 0
and 1, resulting an unbalanced STI connections across books.
To optimize Reliability, Availability, and Serviceability (RAS) characteristics of the server, the
STI Rebalance feature (Feature Code 2400) can be ordered on server upgrades, including
additional books.
STI Rebalance feature (Feature Code 2400)
Figure 3-6 on page 82 shows the previous server upgrade example, from a 2084-B16 to a
model D32, with the STI Rebalance feature (FC 2400) selected for the upgrade of the
configuration.
2084-D32 CEC Cage
I/O Cage 1 I/O Cage 2
Book 0 Book 1
STIs
I/O Domains
STI Links
I/O Cards
MBA
0
MBA
1
MBA
2
MBA
0
MBA
1
MBA
2
Book 2 Book 3
MBA
0
MBA
1
MBA
2
MBA
0
MBA
1
MBA
2