Independent channel recovery with replay buffers on all interfaces allows recovery of a single  DIMM channel, while other channels remain active. Further redundancies are incorporated in  I/O pins for clock lines to main memory, which eliminates the loss of memory clocks because  of connector (pin) failure. The following RAS enhancements reduce service complexity: IBM Z RAS efforts focus on the reduction of unscheduled, scheduled, planned, and  unplanned outages. IBM Z technology has a long history of demonstrated RAS  improvements, and this effort continues with changes that reduce service  touches  on the  system.  Firmware was updated to improve filtering and resolution of errors that do not require action.  Enhanced integrated sparing in processor cores, cache relocates, N+1 SEEPROM and POL  N+2 redundancies, and DRAM marking also are incorporated to reduce touches. The  following RAS enhancements reduce service touches: The following functions include availability characteristics on z15 servers: 386  IBM z15 (8561) Technical Guide 9.6 z15 availability characteristics 9.5 Reducing touches GLYPH<SM590000> Continued use of RAIM ECC. GLYPH<SM590000> No cascading of memory DIMM to simplify the recovery design. GLYPH<SM590000> Replay buffer for hardware retry on soft errors on the main memory interface. GLYPH<SM590000> Redundant I/O pins for clock lines to main memory. GLYPH<SM590000> Improved error resolution to enable filtering GLYPH<SM590000> Enhanced integrated sparing in processor cores GLYPH<SM590000> Cache relocates GLYPH<SM590000> N+1 SEEPROM GLYPH<SM590000> N+2 POL GLYPH<SM590000> DRAM marking GLYPH<SM590000> (Dynamic) Spare lanes for PU-SC, PU-PU, PU-mem, and SC-SMP fabric GLYPH<SM590000> N+1 radiator pumps, controllers, blowers, and sensors GLYPH<SM590000> N+1 Ethernet switches GLYPH<SM590000> N+1 Support Element (SE) (with N+1 SE power supplies) GLYPH<SM590000> Redundant SEEPROM on memory DIMM GLYPH<SM590000> Redundant temperature sensor (one SEEPROM and one temperature sensor per I 2 C  bus) GLYPH<SM590000> FICON forward error correction  GLYPH<SM590000> Enhanced drawer availability (EDA)  GLYPH<SM590000> Concurrent memory upgrade or replacement EDA is a  procedure  under which a CPC drawer in a multidrawer system can be removed  and reinstalled during an upgrade or repair action with no effect on the workload.  Memory can be upgraded concurrently by using Licensed Internal Code Configuration  Control (LICCC) if physical memory is available on the drawers. 