IBM Cloud Pak System

A tour of the hardware in IBM Cloud Pak System: The fourth generation

By Hendrik van Run posted 19 days ago

Originally published as IBM Developer Recipe here on 13 October 2020 by Hendrik van Run and Joe Wigglesworth.


IBM announced the IBM Cloud Pak System W4600 on Tue 6th October 2020, which has been available since Mon 12th October 2020. This article describes the models and hardware in these systems, comparing them with earlier generations.

What is IBM Cloud Pak System

IBM Cloud Pak System is a turnkey modular cloud for IBM Cloud Paks that can be deployed in a client's on-premises data center. It provides a cloud-computing-in-a-box experience with its integrated hardware and software. It delivers automation provided through IBM Cloud Pak System accelerators to quickly deploy workloads, including IBM Cloud Paks, Red Hat OpenShift Container Platform, and IBM Edge Application Manager. In addition, it continues to provide first-class support for the deployment of IBM WebSphere, IBM Liberty, IBM Db2, and IBM Spectrum Scale. This helps dramatically decrease the time-to-value and lowers the total cost of ownership, while at the same time allowing clients to modernize and containerize their applications at their own pace.

Figure 1: IBM Cloud Pak System W4600


The fourth generation of IBM Cloud Pak System hardware, the W4600, was announced on October 6, 2020, and is generally available from October 12, 2020. In a nutshell, the following are the differences between the W4600 and the third generation models, such as W3500 and W3550:

  • All Intel Xeon Cascade Lake processors in the compute nodes and the PSM (Platform System Manager) nodes
  • Two different compute node models: 16 cores with 640 GB RAM and 32 cores with 1536 GB RAM
  • Built-in IBM FlashSystem 7200 storage subsystem with 32 Gbps Fibre Channel adapters
  • 45 TB built-in all-flash storage using IBM NVMe FlashCore modules
  • NVIDIA Mellanox Spectrum SN2410 top-of-rack switches with 25 Gbps Ethernet support running the NVIDIA Cumulus Linux

Let’s review each of these changes in detail.

IBM Cloud Pak System models

The workload hosting environment of a system is determined by its architecture. The IBM Cloud Pak System model W4600 is based on the Intel x86-64 architecture, as shown in Table 1.

Table 1. IBM Cloud Pak System W4600 architecture
Model System architecture Machine type Processor Hypervisor Workload operating system
W4600 Intel x86-64 9668-CVM Intel Xeon Cascade Lake VMware vSphere Red Hat Enterprise Linux (RHEL) or Microsoft Windows Server

IBM Cloud Pak System model W4600 represents the fourth generation, as shown in Table 2.

Table 2. Evolution of IBM Cloud Pak System generations
Generation Name at launch Intel Models Power Models Comments
First IBM PureApplication System W1500 W1700 End of Support - 30 Sep 2019
Second IBM PureApplication System W2500 W2700 End of Support - 30 Sep 2021
Third IBM Bluemix Local System W3500, W3550 W3700
Fourth IBM Cloud Pak System W4600 TBC

Unlike earlier generations, the fourth generation of the IBM Cloud Pak System offers two different types of compute nodes, namely Regular and Regular Expanded. IBM has chosen for Lenovo ThinkSystem SR630 Rack Servers as compute nodes in the W4600. As shown in Table 3, the two types provide flexibility regarding the number of cores and the amount of RAM per compute node. The compute nodes are available in pairs, but the types can be mixed within the same system. For example, a single W4600 system can have four Regular compute nodes and six Regular Expanded compute nodes.

Table 3. Two types of compute nodes are available for use in the fourth generation IBM Cloud Pak System W4600
Compute Node Type Number of cores per compute node RAM per compute node RAM per core
Regular 16 640 GB 40 GB
Regular Expanded 32 1536 GB 48 GB

Note that the support for mixing Regular and Regular Expanded compute nodes has implications for System HA. In that scenario, IBM recommends to associate Regular Expanded compute nodes to the HA cloud group. That way, planned or unplanned downtime of any compute node can be handled.

As both compute node types available for IBM Cloud Pak System W4600 are based on Intel Cascade Lake processors, there is no need to configure EVC, as documented in this Knowledge Center. However, this could change if and when IBM release compute nodes using a processor based on a new micro-architecture. The size of a system describes the number of compute nodes in it and is upgradeable in increments of 2 compute nodes to a maximum of 22. The upgrades to the size of the system without taking an outage is similar to upgrades to the IBM Cloud Pak System firmware.

It is always worth comparing the compute nodes with those from earlier generations. Table 4 includes compute node specifications for the W4600 compute nodes, as well as those of second and third generation Intel models. The newer Intel processors in IBM Cloud Pak System continue to provide solid performance. The 2.5 GHz clock speed of the processors of the Regular and Regular Expanded compute node types is lower than the 3.0 GHz of the Third3+ compute nodes. However, a Regular W4600 compute node outperforms a Third+ compute node by about 6%, and the Regular Expanded W4600 outperforms it by about 47%.

Table 4. Comparing Compute Nodes in IBM Cloud Pak System W4600 to those from earlier generations
Generation Model Compute Node Type Number of cores Processor micro-architecture CPU model RAM
Fourth W4600 Regular Expanded 32 Cascade Lake 16 core, 2.1 GHz Intel Xeon Gold 5218T (105W) 1536 GB
Fourth W4600 Regular 16 Cascade Lake 8 core, 2.5 GHz Intel Xeon Silver 4215 (85W) 640 GB
Third+ W3550 - 16 Cascade Lake 8 core, 3.0 GHz Intel Xeon Gold 5217 (115W) 768 GB
Third+ W3500 - 16 Cascade Lake 8 core, 3.0 GHz Intel Xeon Gold 5217 (115W) 512 GB
Third W3550 - 16 Broadwell 8 core, 3.2 GHz Intel Xeon E5-2667 v4 (135 W) 768 GB
Third W3500 - 16 Broadwell 8 core, 3.2 GHz Intel Xeon E5-2667 v4 (135 W) 512 GB
Second W2500 Enterprise 16 Ivy Bridge 8 core, 2.6 GHz Intel Xeon Processor E5-2650 v2 (115 W) 512 GB
Second W2500 Mini 16 Ivy Bridge 8 core, 2.6 GHz Intel Xeon Processor E5-2650 v2 (115 W) 256 GB

Note: IBM Cloud Pak System W3500/W3550 models that shipped after November 2019 included Cascade Lake processors and are therefor referred to as "Third+" generation models.

There is now just a single 7-digit machine type model (MTM) for the IBM Cloud Pak System W4600 itself. Unlike earlier generations, there is no longer a range of different 7-digit machine type model depending on the number of installed compute nodes. Instead, IBM introduced separate machine type models for the compute node upgrades. Please refer to the IBM Cloud Pak System W4600 announcement letter or Table 5 for the machine type models.

Table 5. Simplified Machine Type Models for IBM Cloud Pak System W4600
Machine Type Model IBM Cloud Pak System model Product name Capacity
9568-CVM W4600 Performance Base System -
9573-LRC W4600 Two "Regular" Compute Node upgrade 32 cores / 1280 GB RAM
9573-LLC W4600 Two "Regular Expanded" Compute Node upgrade 64 cores / 3072 GB RAM
9633-IRS W4600 Storage Expansion 150 TB

Using the machine type models from Table 5, you can easily determine what you need to order to achieve the desired storage capacity of your IBM Cloud Pak System W4600. Table 6 below describes the options available. Note that the storage expansions (machine type model 9633-IRS) can be installed from the start, or ordered and installed later.

For more storage, the IBM Cloud Pak System W4600 supports up to 17 additional 150 TB storage expansions, which must be installed outside the base system. They are connected through to the SAS controllers, giving the same performance characteristics as the storage inside the base system.

And just like with the IBM Cloud Pak System W3550, the W4600 continues to provide support for integration with external storage by connecting the fibre channel fabric to an IBM SAN Volume Controller outside the base system (as documented here in the Knowledge Center).

Table 6. Simplified Machine Type Models for IBM Cloud Pak System W4600
Description 9568-CVM 9633-IRS Total Effective Usable Storage Capacity
System without storage expansions 1 0 45 TB
System with one storage expansion 1 1 150 + 45 = 195 TB
System with two storage expansion 1 2 300 + 45 = 345 TB
System with three storage expansion 1 3 450 + 45 = 495 TB

Table 7 provides a comprehensive overview of all the hardware components found in an IBM Cloud Pak System W4600 model.

Table 7. Fourth generation IBM Cloud Pak System hardware specifications
W4600 Regular W4600 Regular Expanded
Compute Number of Compute nodes 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22
Number of CPU cores 16 cores per server 32 cores per server
Amount of Memory in TB 640 GB RAM per server 1.5 TB RAM per Server
Compute node Lenovo SR630 2-socket Lenovo SR630 2-socket
Processor 2 x Intel Xeon Silver 8 core (4215) 2.5GHz (Cascade Lake) 85W 2 x Intel Xeon Gold 16 core (5218T) 2.1GHz (Cascade Lake) 105W
Network adapter 2 x Mellanox ConnectX-4 Lx 10/25GbE SFP28 2-port PCIe Ethernet Adapter
Storage Storage adapter Emulex LPE 35002 Dual Port 32 Gb Fibre Channel HBA, PCIeLow Profile (int/ext storage support
Storage controller IBM FlashSystem 7200 Enclosure (2076-824) w/ Dual Controllers & enhanced cache
Storage network Fibre Channel
Storage switches 2 x IBM System Storage SAN64B-6 32 Gb Fibre Channel
Base storage volume 8 x 4.8 TB IBM FlashCore Modules w/ self-compression & self-encryption (optional)
Total included storage 45 TB effective [2:1 compressed] in Distributed RAID 6 (NVMe)
Expansion storage Optional: IBM Expansion Storage Array (2076-24G)
Expansion storage volume 150 TB effective (per expansion) in Distributed RAID 6 (SAS SSD)
Total expansion storage 495 TB effective [2:1 compressed for base] (w/ 3 x expansions) in Distributed RAID 6
Network Top of Rack Switches 2 x NVIDIA Mellanox SN2410 TOR 25 Gb E w/ Cumulus Linux
Internal Switches 2 x NVIDIA Mellanox Select AS4610-54T Internal Mgmt 1 Gb E w/ Cumulus Linux
Available Customer Uplink Ports 8 x 1/10/25GbE
Management Management Nodes 2 x Lenovo SR630 Platform Software Manager (PSM) w/640 GB RAM, 20 cores, 7.68 TB SSD
Power Power Distribution Unit (PDU) 6 x 30A single phase or 32A three phase wye
Rack Rack 2.0 M 19” 42U Constellation Rack
Physical Dimensions Height: 2,020 mm (79.5 in) / Depth: 1,200 mm (47.2 in) / Width: 600 mm (23.6 in)
Weight (kg, lbs) [Rack w/ extender] Minimum 436 kg / 959 lbs; Maximum: 875 kg / 1924 lbs

Anyone familiar with earlier generations of IBM Cloud Pak System will recognize the following basic components in the fourth generation models:

  • A pair of management servers,
  • Two or more compute nodes with CPU and RAM but no storage,
  • A storage controller with a significant amount of storage,
  • A pair of top of rack (ToR) switches,
  • A pair of Fibre Channel switches,
  • A pair of management network switches,
  • A service terminal with keyboard, video and mouse,
  • Power distribution units (PDUs), and
  • A 42U rack with rear extender and ballast.

However, the fourth generation hardware makes a number of changes to the specifications of components. It also makes adjustments to the contents of a compute node. The Figure 2 illustrates the layout of the hardware components in an IBM Cloud Pak system W4600.

Figure 2: IBM Cloud Pak System W4600

As always, every hardware component is made redundant to avoid a single point of failure. Taking a closer look at each component, the following changes can be noted:

  • Compute nodes: The most significant change in generation four hardware is the introduction of the choice of compute nodes. Each system in the previous generations had only one compute node configuration, whereas, generation four has two configurations, namely Regular and Regular expanded. The Regular compute nodes are 16 core server with 40 GB of RAM per core. The Regular expanded compute nodes have 32 cores and 48 GB of RAM per core. More details on these compute node options are available in Table 7.
  • Data network: A pair of NVIDIA Mellanox Spectrum SN2410 switches provide the data network within the system. They provide a significant improvement in network speed over the previous generation that used 10 Gbps switches. These switches run the Cumulus Linux OS. All compute nodes have two connections to each of the switches.
  • Management network: A pair of NVIDIA Mellanox Select AS4610-54T switches provide the management network within the system. These Ethernet switches also run the Cumulus Linux OS.
  • SAN network: The Fibre Channel storage network within the system has also had a bandwidth upgrade. The 16 Gbps Fibre Channel switches have been replaced by a pair of 32 Gbps Fibre Channel switches.
  • Storage controller: The IBM FlashSystem 7200 storage controller is the latest model in the line of IBM Spectrum Virtualize storage controllers that included the Storwize V7000 used in some third generation systems.
  • Power: Six PDUs provide the needed amount of power and redundancy for all system components. It is necessary to use only four of the six PDUs for systems that have 12 or fewer compute nodes and no more than one storage expansion.
  • Cabinet: The cabinet that houses the system is the same height but a bit narrower. On the back of the cabinet is extension to provide more room for cable management. There are no longer any chassis in the cabinet as there were in the W3550 model of the previous generation.


In this article, we reviewed the fourth generation of IBM Cloud Pak System hardware, focusing primarily on differences from the third generation. It explained what hardware components are contained in the various models, and the hardware improvements inside the compute nodes. With this information, you should have a better understanding of the hardware included in the latest IBM Cloud Pak System.


The authors would like to thank fellow IBMers David Salinas, Hugh Hockett and Shyamala Rajagopalan for their help with this article.