C.1.3 Resource groups The IFP allocates four resource groups for running the management functions of native PCIe  adapters. A native PCIe adapter is managed by one of the resource groups according to the  adapter location in the PCIe+ I/O drawer.  As shown in Figure C-1, each I/O domain in a PCIe+ I/O drawer of a z14 ZR1 server is driven  by a PCIe switch that is connected to the PCIe I/O feature that is in the CPC drawer. Each slot  in a PCIe_ I/O drawer is attached to one resource group. The native PCIe I/O adapters are  managed by their respective RG for device drivers and diagnostic tools functions. Up to four PCIe+ I/O drawers are supported on z14 ZR1 servers. The same type of native  PCIe adapter is always assigned to different I/O domains and in different resource groups  (and different PCIe I/O drawers if the configuration includes them) to eliminate the possibility  of a single point of failure. Figure C-1 I/O domains and resource groups that are managed by the IFP - z14 ZR1 C.1.4 Service and management tasks Firmware update of adapters and resource groups The IFP and resource groups perform the following management tasks on the native PCIe  adapters: The firmware of native PCIe adapters and resource groups is part of the system’s microcode  and can be updated by a Microcode Change Level (MCL) upgrade. MCL upgrades on  adapters or on the code of the resource groups require the specific adapter or all native PCIe  adapters that are managed by the specific resource group (depending on the type of  microcode that it applied) to be offline during activation of the MCL.  GLYPH<SM590000> Firmware update of adapters and resource groups GLYPH<SM590000> Error recovery and failure data collection GLYPH<SM590000> Diagnostic and service tasks Appendix C. Native Peripheral Component Interconnect Express  421