## 2.1 Frames and configurations 

The z15 Model T01 system is designed in a 19-inch form factor with configuration of 1 - 4 frames that can be easily installed in any data center. The z15 Machine Type 8561 can include 1 - 4 42U EIA (19-inch) frames, which are bolted together. The configurations can include up to five central processor complex (CPC) drawers and up to 12 Peripheral Component Interconnect Express+ (PCIe+) I/O drawers. 

The redesigned CPC drawer and I/O infrastructure also lowers power consumption, reduces the footprint, and allows installation in virtually any data center. The z15 server is rated for ASHRAE class A3$^{1}$ data center operating environment. 

The z15 server differentiates itself from previous Z server generations through the following significant changes to the modular hardware: 

GLYPH<SM590000> All external cabling (power, I/O, and management) is performed at the rear of the system 

GLYPH<SM590000> Flexible configurations: Frame quantity is determined by the system configuration (1 - 4 frames) 

GLYPH<SM590000> Choice of power Intelligent Power Distribution Unit (iPDU or PDU) or Bulk Power Assembly (BPA) 

GLYPH<SM590000> Feature codes that reserve slots for plan-ahead CPC drawers 

GLYPH<SM590000> Added internal water cooling plumbing for systems with more than three CPC drawers 

GLYPH<SM590000> New PCIe+ Gen3 I/O drawers (19-inch format) supporting 16 PCIe adapters 

The power options include PDU-based power or BPA-based power. The z15 server can be configured as a radiator (air) cooled or water cooled (that uses data center chilled water supply) system. Only BPA-based power system can be (optionally) configured for water cooling and with Internal Battery Feature (IBM), while a radiator (air) cooled system has PDU-based power (no Internal Battery Feature [IBF] available for PDU-based systems). 

The z15 includes the following basic hardware building blocks: 

GLYPH<SM590000> 19-inch 42u frame (1 - 4) 

GLYPH<SM590000> CPC (Processor) drawers (1 - 5) 

GLYPH<SM590000> PCIe+ Gen3 I/O drawers (up to 12) 

GLYPH<SM590000> CPC drawer Cooling Units: Radiator cooling assembly (RCA) or Water Cooling Unit (WCU) 

GLYPH<SM590000> Power, with choice of: 

– Intelligent Power Distribution Units (iPDU) pairs (2 - 4 per frame, depending on the configuration). 

– Bulk Power Regulators (1 - 6 pairs, depending on the configuration) 

GLYPH<SM590000> Support Elements (two): 

–S i n g l e  K M $^{2}$ device (USB-C connection) 

– Optional extra hardware for IBM Hardware Management Appliance feature 

GLYPH<SM590000> 24-port 1GbE Switches (two or four, depending on the system configuration) 

GLYPH<SM590000> Hardware for cable management at the rear of the system 

