By now you have seen much of the press on IBM’s new Linux server called LinuxONE™ supporting very large numbers of virtual machines, with up to 10 TB of memory, and a CPU that can run your Linux business applications at up to 5 GHz. LinuxONE is built on IBM z Systems™ technology, and other features it shares with IBM z Systems include a very secure system with advanced encryption features built into the hardware and software, and a system that enables key open source and industry software for LinuxONE and IBM z Systems.
The advantages of a highly resilient Linux server are must-haves for supporting the emerging cloud, analytic and mobile server platforms. LinuxONE systems inherit the strengths and capability of the IBM z13 system, repackaged for the Linux and cloud environment with security, availability, resource allocation, workload management and dynamic scaling.
This all sounds great so far, right? Yes, but the marketing descriptions leave some technical professionals wanting more facts, again asking “why should I host my Linux guests on IBM z Systems or IBM LinuxONE?
It is very true that Linux and KVM for IBM z Systems inherit all of the benefits of the z Systems hardware. The historic strengths of z Systems (reliability, availability and serviceability) when aligned with the stability and openness of Linux, provides a strong platform for hosting your business applications on Linux servers. The following are areas that particularly benefit applications deployed on z13 and LinuxONE systems:
- Hardware-enabled virtualization allows KVM for IBM z to host many guest virtual servers in a single logical partition (LPAR), while supporting multiple LPARs on a single system, by sharing resources such as CPU and device adapters across virtual servers. This provides an environment where multiple Linux servers hosted by KVM for IBM z Systems can do the job of many distributed systems in an IT enterprise. In addition, memory and CPU over-commitment further enables hosting of guests at a very large scale. The high scalability also reduces the number of physical servers and amount of networking infrastructure, reducing the overall Total Cost of Ownership (TCO) … not to mention savings in cooling, maintenance, power, software support and infrastructure costs. The z Systems hardware is designed from the ground up to optimize virtualization.
- Security: Linux security and integrity features are further extended on z Systems by integrating hardware-based security features into the operating environment. This includes encryption and cryptographic solutions to help secure data from leakage threats. The Common Criteria certification (EAL 5+) of the z13 hardware partitioning (LPAR) ensures that two KVM for IBM z hosts running in different LPARs on the same physical system can be configured to be fully isolated.
- High Availability: Multiple partitions deliver very high levels of hardware and firmware redundancy, allowing each to be an excellent host for your Linux guests. Similarly, high availability of KVM for IBM z Systems guests can be achieved by leveraging Linux resource management (bonded network adapters, multi-path disk access, etc.). Middleware such as Websphere Application Server Network Deployment or DB2 HADR support automated failover to alternate KVM guests in the defined cluster.
- Input/Output (I/O) virtualization: KVM for IBM z Systems I/O virtualization enables sharing of physical I/O resources among virtual servers, supporting an array of virtualized I/O configurations, including Fiber Channel (FC) and Enhanced Count Key Data (ECKD) storage and OSA network cards. This includes:
- Sharing of physical I/O resources
- Dynamic addition and deletion of virtual I/O devices, eliminating the need for downtime to modify I/O device configurations for virtual servers
- Live virtual server migration: KVM for IBM z Systems supports live migration of virtual servers between different KVM for IBM z hosts running in different partitions that may or may not be located on different IBM z Systems servers allowing business applications to remain active during a scheduled outage of a hypervisor image.
- Management capabilities of KVM for IBM z Systems are provided by libvirt APIs, which enable command line interfaces (CLIs) to be used to administer the hypervisor resources and virtual machines. Furthermore, KVM for IBM z can be monitored and administered using open source tools such as Nagios, Ganglia, and OpenStack.
- Hardware-enabled availability features: Linux for z Systems also supports high availability features provided by the z Systems hardware such as dual power supplies, dynamic firmware updates, dynamic I/O reconfiguration, First Failure Data Capture (FFDC) collection/analysis, error isolation, recovering from machine checks and I/O errors and the ability to dynamically vary devices on and off.
- Memory robustness: Computers have historically had memory DIMM problems. The newer “RAIM memory” technology is designed to eliminate server failures due to memory crashes. In the last three hardware generations, since IBM introduced RAIM memory technology, z Systems have had no server failures due to memory crashes. RAIM memory provides extreme high availability, meaning customers do not face the risk of downtime as they might have in the past using traditional DRAM technology.
- Concurrent repair: Linux running on a z Systems server inherits the full z Systems RAS, the hardware and firmware recovery, error checking, diagnostics, tracing and concurrent repair. Hardware failures do not mean that the operating system, or the applications, noticed. That’s because 97% of the repair actions (based on field data) are fully concurrent. That means mobile applications can keep accessing their data, databases keep warehousing data, and sales terminals can keep selling.
Your Linux on z Systems applications inherit all of these strengths, providing an outstanding platform to host your Linux business applications with huge scale and room to grow! Furthermore, open source virtualization of Linux guests hosted by KVM for IBM z Systems also inherit these strengths, giving you a cost-effective alternative to proprietary x86 virtualization. Instead of asking why host key business applications on Linux on z Systems or LinuxONE, perhaps the question is why not?
Bob Abrams, Bill Clarke
IBM Poughkeepsie, NY
 IBM Systems Magazine, ibmsystemsmag.com, August 2015
 The ECKD storage architecture in Linux defines disks formatted as “arrays” of fixed size (4K byte) blocks. ECKD refers to a set of channel commands (collectively Channel Command Words, CCWs) that are accepted by a disk subsystem employing the ECKD recording format.
 The Open Systems Adapter (OSA) is a network controller installed in an IBM z Systems I/O cage. The adapter integrates several hardware features and supports many networking transport protocols. For more information, see the OSA-Express Implementation Guide, www.redbooks.ibm.com/abstracts/sg245948.html