The POWER9 processor that is used in the DS8900F operates in simultaneous multithreading (SMT) mode, which executes multiple instruction streams in parallel. The number of simultaneous instruction streams varies according to processor and Licensed Internal Code (LIC) level. SMT mode enables the POWER9 processor to maximize the throughput of the processor cores by offering an increase in core efficiency. 

The DS8900F configuration options are based on the total installed memory, which in turn corresponds to a predetermined number of installed and active processor cores. 

The following DS8910F configuration upgrade can be performed nondisruptively: 

GLYPH<SM590000> Memory upgrade from 96 GB / server to 256 GB / server. 

The following DS8950F configuration upgrades can be performed nondisruptively: 

GLYPH<SM590000> Processor configuration upgrade from 10 cores / server to 20 cores / server. 

GLYPH<SM590000> Memory upgrade from 256 GB / server to 512 GB / server or 1024 GB / server. 

GLYPH<SM590000> Memory upgrade from 512 GB / server to 1024 GB / server. 

Note:  System memory and processor upgrades are tightly coupled. They cannot be ordered or installed independently from each other. 

Caching  is a fundamental technique for reducing I/O latency. Like other modern caches, the DS9000F contains volatile memory (RDIMM) that is used as a read and write cache and nonvolatile memory (NVDIMM) that is used for Persistent Memory Write Cahe. It eliminates the need for DC-UPS and special stocking of batteries. If power is lost, the system shuts down completely in 20 ms, but the power is maintained to all of the NVDIMMs to write all data in nonvolatile (NVS) storage to the NAND flash on the NVDIMMs. 

The NVS scales to the processor memory that is installed, which also helps to optimize performance. NVS is typically 1/16th of installed CPC memory, with a minimum of 8 GB and a maximum of 128 GB. 

## 2.3.3 Flexible service processor 

Each Power9 processor complex is managed by a service processor that is called a flexible service processor (FSP). The FSP is an embedded controller that is based on an IBM PowerPCfi processor. 

The FSP controls power and cooling for the CPC. The FSP performs predictive failure analysis for installed processor hardware, and performs recovery actions for processor or memory errors. The FSP monitors the operation of the firmware during the boot process, and can monitor the operating system for loss of control and take corrective actions. 

## 2.3.4 Ethernet Connections 

Each Power9 processor complex has a single four-port 1 Gbps Ethernet card installed. On all models, the top two of these ports are connected to the internal network switches described in Figure 2-31 on page 62. The bottom two RJ45 copper ports can be used for Transparent Cloud Tiering (TCT). 

A new optional adapter is available for TCT as a chargeable feature code, and gives 2 high speed 10 Gbps SFP+ optical ports for short reach (SR) and two low speed 1 Gbps (RJ45 copper) connectors. The 1Gbps ethernet card is in the same slot for DS8910F and DS8950F (P1-C11). The 10Gbps ethernet card is in the P1-C4 slot for DS8910F and in the P1-C10 slot for DS8950F.For details about TCT, see “Transparent Cloud Tiering” on page 158. 

