GLYPH<SM590000> Air-cooled system: radiator with redundant ( N +1) pumps. GLYPH<SM590000> Water-cooled system: N+1 Water-Cooling Units (WCUs). GLYPH<SM590000> Hot-swap IFB hub cards. GLYPH<SM590000> Redundant 1 Gbps Ethernet service network with virtual LAN (VLAN). GLYPH<SM590000> The PCIe I/O drawer is available for z14 servers. It and all of the PCIe I/O  GLYPH<SM590000> Memory interface logic to maintain channel synchronization when one channel goes into  replay. z14 servers can isolate recovery to only the failing channel. GLYPH<SM590000> Out of band access to DIMM (for background maintenance functions).  GLYPH<SM590000> Lane shadowing function to each lane that periodically is taken offline (for recalibration). GLYPH<SM590000> Automatic lane recalibration on offline lanes on the main memory interface. Hardware  support for transparent recalibration is included. GLYPH<SM590000> Automatic dynamic lane sparing based on pre-programmed CRC thresholds on the main  memory interface. Hardware support to detect a defective lane and spare it out is  included. GLYPH<SM590000> Improved DIMM exerciser for testing memory during IML. GLYPH<SM590000> PCIe redrive hub cards plug straight in (no blind mating of connector). Simplified plugging  that is more reliable is included. GLYPH<SM590000> ICA (short distance) coupling cards plug straight in (no blind mating of connector).  Simplified plugging that is more reliable is included. GLYPH<SM590000> Coupling Express LR (CE LR) coupling cards plug into the PCIe I/O Drawer, which allows  more connections with a faster bandwidth. GLYPH<SM590000> Hardware-driven dynamic lane sparing on fabric (SMP) buses. Increased bit lane sparing  is featured. The (logical) spare bit lane is rotated through the (physical) lanes. This configuration  allows the lane to be tested and recalibrated transparently to customer operations. Out of band access (by using an I 2 C interface) allows maintenance (such as logging)  without disrupting customer memory accesses. drawer-supported features can be installed concurrently. The service network in the system gives the machine code the capability to monitor each  internal function in the system. This process helps to identify problems, maintain the  redundancy, and concurrently replace a part. Through the implementation of the VLAN to  the redundant internal Ethernet service network, these advantages are improved, which  makes the service network easier to handle and more flexible. z14 servers implement true  N +1 redundancy on pumps and blowers for the radiator. The  radiator cooling system can support one and two CPC drawers simultaneously with a  redundant design that consists of two pumps and two blowers. One active pump and  blower can support the entire system load. If you have three or four CPC drawers, one  extra blower is available, and one active pump and two blowers can support the entire  system load. The replacement of a pump or blower causes no performance effect.  A water-cooling system is an option in z14 servers with WCU technology. Two redundant  WCUs run with two independent chilled water feeds. One WCU and one water feed can  support the entire system load. The water-cooled configuration is backed up by the rear  door heat exchangers in the rare event of a problem with the chilled water facilities of the  customer. When correctly configured for redundancy, hot swapping (replacing) the IFB (HCA2-O  [12xIFB] or HCA3-O [12xIFB]) hub cards is possible. This process avoids any interruption  when you must replace these types of cards. 374  IBM z14 (3906) Technical Guide