Although CBU and On/Off Capacity on Demand can both reside on the server, the activation of On/Off Capacity on Demand is mutually exclusive with Capacity BackUp (CBU) and no physical hardware upgrade will be sup- ported while On/Off Capacity on Demand is active.
This important new function for zSeries gives customers greater control and ability to add capacity to meet the requirements of an unpredictable on demand applica- tion environment. On/Off CoD extends zSeries capacity on demand offerings to the next level of fl exibility. It is designed to help customers match cost with capacity utilization and manage periodic business spikes. On/Off Capacity on Demand is designed to provide a
Customers can also take advantage of Capacity Upgrade on Demand (CUoD), Customer Initiated Upgrade (CIU), and Capacity BackUp (CBU) which are described later in the document.
The z990 has also been designed to offer a high perfor- mance and effi cient I/O structure. All z990 models ship with two frames the
and up to 360 ESCON channels. Each book will support up to 12 STIs for I/O connectivity. Seven STIs are required to support the 28 channel slots in each I/O cage so in order to support a fully confi gured three I/O cage system 21 STIs are required. To achieve this maximum I/O con- nectivity requires at least a B16 model which provides 24 STIs.
The following chart shows the upgrade from z900 to z990. There are any to any upgrades from any of the z900 gen- eral purpose models. A z900 Coupling Facility Model 100 must fi rst be upgraded to a z900 general purpose model before upgrading to a z990. There are no upgrades from 9672 G5/G6 or IBM ^zSeries 800 (z800).
Model Upgrades
z900 | z990 |
100
101 - 109 
A08
1C1 - 116
B16
2C1 - 216 | C24 |
D32
11