The following items are present in the z14 ZR1 server, but they are not part of the PUs that  clients purchase and require no characterization: The various feature code driven CPC drawer sizes are listed in Table 2-1 on page 37. A  capacity marker  identifies the number of CPs that were purchased. This number of  purchased CPs is higher than or equal to the number of CPs that is actively used. The  capacity marker marks the availability of purchased but unused capacity that is intended to be  used as CPs in the future. They often have this status for software-charging reasons. Unused  CPs are not a factor when establishing the millions of service units (MSU) value that is used  for charging monthly license charge (MLC) software, or when charged on a per-processor  basis. Concurrent upgrades of CPs, IFLs, ICFs, zIIPs, or SAPs are available for the z14 ZR1 server.  However, concurrent PU upgrades require that more PUs are installed, but not activated.  The spare PU is used to replace defective PUs. In the rare event of a PU failure, a spare PU is  activated concurrently and transparently and is assigned the characteristics of the failing PU.  If an upgrade request cannot be accomplished within the configuration, a hardware upgrade  is required. The upgrade that requires the addition of one or more PU SCMs and DIMMs per  to accommodate the wanted capacity. All upgrades for z14 ZR1 that involve adding PU SCMs or memory are disruptive.  The upgrade paths for the z14 are shown in Figure 2-23. GLYPH<SM590000> Standard SAP to be used by the channel subsystem. The number of standard SAPs is  always two. GLYPH<SM590000> One IFP (Integrated Firmware Processor), which is used in the support of “native” PCIe  features. GLYPH<SM590000> One spare PU, which can transparently assume any characterization if another PU a  permanent fails. 2.7.3 System upgrades Figure 2-23 z14 ZR1 system upgrade paths 52  IBM 14 Model ZR1 Technical Guide