Chapter 5. Availability 95
support and appropriate planning, concurrent upgrades
can also be nondisruptive to the operating system. Such
upgrades provide additional capacity (memory,
processors) without a server outage.
Capacity upgrades can be either permanent or temporary:
- Capacity Upgrade on Demand (CUoD)
- Customer Initiated Upgrade (CIU)
- On/Off Capacity on Demand (On/Off CoD)
- Capacity BackUp (CBU)
Refer to 3.3.6, “Workload Manager (WLM)” on page 56 to
learn more about CUoD, CIU, and OOCoD. Concepts
such as dynamic, nondisruptive addition of processor
resources like processors, memory and I/O for permanent
use reduce the need for planned outages.
Capacity Backup (CBU)
Capacity Backup (CBU) is the temporary activation of CPs, IFLs, ICFs, zAAPs
and zIIPs for robust disaster recovery. The CBU features provide the ability to
concurrently increment the CP or specialty engine capacity of your System z
server, using Licensed Internal Code, Control Code (LIC-CC), in the event of an
unforeseen loss of substantial System z computing capacity at one or more sites.
The CBU features contain additional resources and alter the target server to an
agreed-upon configuration for up to a 90-day period.
5.4.2 Accessing peripheral devices
In a continuous availability environment, keep the following points in mind when
configuring the peripherals.
Create a configuration that will survive the loss of any single component
within the subsystem.
Configure your storage subsystem such that you can survive, or at least
recover from, a complete loss of the whole subsystem.
Mirror your data such you can survive even if you lost a storage subsystem, or
even a complete data center.