This capability is based on the flexibility of the design and structure, which allows concurrent  hardware installation and Licensed Internal Code (LIC) control over the configuration. Subcapacity models provide for a CP capacity increase in two dimensions that can be used  together to deliver configuration granularity. The first dimension is by adding CPs to the  configuration, and the second dimension is by changing the capacity setting of the CPs  currently installed to a higher MCI. In addition, a capacity increase can be delivered by  increasing the CP capacity setting, and at the same time decreasing the number of active  CPs.  Consideration:  A z14 ZR1 Max4 has a maximum of four PUs available, so it can  concurrently be upgraded to models A04 - Z04. If a capacity setting with more than four  CPs is required or the combination of CPs and specialty engines exceeds four, a  non-concurrent upgrade to a CPC drawer Max12 feature (FC 0637)$^{a}$ is required. z14 ZR1 servers allow the concurrent and nondisruptive addition of processors to a running  logical partition (LPAR). As a result, you can have a flexible infrastructure in which you can  add capacity without pre-planning. This function is supported by z/OS, z/VM, and z/VSE. This  addition is made by using one of the following methods: a. If more specialty engines are needed, Max24 or Max30 feature might be required. GLYPH<SM590000> With planning ahead for the future need of extra processors. Reserved processors can be  specified in the LPAR’s profile. When the extra processors are installed, the number of  active processors for that LPAR can be increased without the need for a partition  reactivation and initial program load (IPL).  GLYPH<SM590000> Another (easier) way is to enable the dynamic addition of processors through the z/OS  LOADxx member. Set the  DYNCPADD  parameter in member LOADxx to  ENABLE . z14 ZR1  servers support dynamic processor addition in the same way that the z14 M0x, z13, z13s,  zEC12, and zBC12 support it. The operating system must be z/OS V1R10 or later. – Feature Max4 (one PU SCM installed) can have a maximum of 4 PUs for client  characterization. GLYPH<SM590000> Machine type and model 3907- ZR1 – Feature Max12 (two PU SCMs) can have a maximum of 12 PUs – Feature Max24 (four PU SCMs) can have a maximum of 24 PUs – Feature Max30 (four PU SCMs) can have a maximum of 30 PUs Another function concerns the system assist processor (SAP). When more SAPs are  concurrently added to the configuration, the SAP-to-channel affinity is dynamically remapped  on all SAPs on the system to rebalance the I/O configuration. z14 ZR1 servers feature the following machine type and model, CPC drawer features, and  model capacity identifiers: The 3907-ZR1 is available in the following CPC drawer features: 8.2.1 Upgrades GLYPH<SM590000> Model capacity identifiers (MCI) are A01 to Z06$^{1}$. The MCI described how many CPs are  characterized (01 - 06) and the capacity setting (A to Z) of the CPs). 1 or an all IFL or all ICF system the capacity identifier is A00.  288  IBM 14 Model ZR1 Technical Guide