2.7.6 Capacity Backup Upgrade CBU and granular capacity Capacity Backup Upgrade (CBU) delivers temporary backup capacity in addition to the  capacity that an installation might have available in numbers of assigned CPs, IFLs, ICFs,  zIIPs, and optional SAPs. CBU has the following types: When CBU for CP is added within the same capacity setting range (indicated by the model  capacity indicator) as the currently assigned PUs, the total number of active PUs (the sum of  all assigned CPs, IFLs, ICFs, zIIPs, and optional SAPs) plus the number of CBUs cannot  exceed the total number of PUs that are available in the system.  When CBU for CP capacity is acquired by switching from one capacity setting to another, no  more CBUs can be requested than the total number of PUs available for that capacity setting. When CBU for CP is ordered, it replaces lost capacity for disaster recovery. Specialty engines  (ICFs, IFLs, and zIIPs) always run at full capacity, and when running as a CBU to replace lost  capacity for disaster recovery.  When you order CBU, specify the maximum number of CPs, ICFs, IFLs, zIIPs, and SAPs to  be activated for disaster recovery. If a disaster occurs, you decide how many of each of the  contracted CBUs of any type to activate. The CBU rights are registered in one or more  records in the CPC. Up to eight records can be active, which can contain various CBU  activation variations that apply to the installation. GLYPH<SM590000> CBU for CP  GLYPH<SM590000> CBU for IFL GLYPH<SM590000> CBU for ICF GLYPH<SM590000> CBU for zIIP GLYPH<SM590000> CBU for more (optional) SAPs GLYPH<SM590000> Number of CP CBUs that are allowed to be activated GLYPH<SM590000> Number of IFL CBUs that are allowed to be activated GLYPH<SM590000> Number of ICF CBUs that are allowed to be activated GLYPH<SM590000> Number of zIIP CBUs that are allowed to be activated GLYPH<SM590000> Number of SAP CBUs that are allowed to be activated GLYPH<SM590000> Number of extra CBU tests that are allowed for this CBU record GLYPH<SM590000> Number of total CBU years ordered (duration of the contract) GLYPH<SM590000> Expiration date of the CBU contract The number of CBU test activations that you can run for no extra fee in each CBU record is  now determined by the number of years that are purchased with the CBU record. For  example, a three-year CBU record includes three test activations, as compared to a one-year  CBU record that has one test activation.  You can increase the number of tests up to a maximum of 15 for each CBU record. The real  activation of CBU lasts up to 90 days with a grace period of two days to prevent sudden  deactivation when the 90-day period expires. The contract duration can be set 1 - 5 years. The CBU record describes the following properties that are related to the CBU: Chapter 2. Central processor complex hardware components  55