For more information about the flexible upgrades that are started by clients, see 8.2.2,  “Customer Initiated Upgrad e facility” on page 324. 9.7.1 Scheduled outages Chapter 9. Reliability, availability, and serviceability  373 Concurrent hardware upgrades, concurrent parts replacement, concurrent driver upgrades,  and concurrent firmware fixes that are available with z14 servers all address the elimination of  scheduled outages. Also, the following indicators and functions that address scheduled  outages are included: GLYPH<SM590000> Double memory data bus lane sparing. This feature reduces the number of repair actions for memory. GLYPH<SM590000> Single memory clock sparing. GLYPH<SM590000> Double DRAM chipkill tolerance. GLYPH<SM590000> Field repair of the cache fabric bus. GLYPH<SM590000> Processor drawer power distribution  N +2 design. GLYPH<SM590000> Redundant N+1 System Control Hubs (SCHs). GLYPH<SM590000> Redundant ( N +2) humidity sensors. GLYPH<SM590000> Redundant ( N +2) altimeter sensors. GLYPH<SM590000> Redundant ( N +2) ambient temperature sensors. GLYPH<SM590000> Dual inline memory module (DIMM) field-replaceable unit (FRU) indicators. GLYPH<SM590000> Single processor core checkstop and sparing. GLYPH<SM590000> Point-to-point fabric for symmetric multiprocessing (SMP). Having fewer components that can fail is an advantage. In a multidrawer system, all of the  drawers are connected by point-to-point connections. A drawer can always be added  concurrently. This indicator shows that a processor core malfunctioned and is  spared . IBM determines  what to do based on the system and the history of that system. These indicators imply that a memory module is not error-free and might fail sometime in  the future. This indicator gives IBM a warning and provides time to concurrently repair the  storage module if the z14 is a multidrawer system.  The process to repair the storage module is to isolate or “fence off” the drawer, remove the  drawer, replace the failing storage module, and then add the drawer. The flexible memory  option might be necessary to maintain sufficient capacity while repairing the storage  module. The CPC Drawer uses point of load (POL) cards in a highly redundant  N +2 configuration.  POL regulators are daughter cards that contain the voltage regulators for the principle  logic voltage boundaries in the z14 CPC drawer. They plug onto the CPC drawer system  board and are nonconcurrent FRUs for the affected drawer, similar to the memory DIMMs.  If you can use EDA, the replacement of POL cards is concurrent for the whole Z server. The bulk power hub (BPH) in former Z servers was repacked into a new part, the SCH.  The SCH contains an Ethernet hub, a flexible support processor (FSP), power supplies for  the SEs and displays, and blowers. Two SCHs are in the A frame for redundancy.