A Jaleel Kavungal

The value of cloud computing is the availability of technological infrastructure support that is always available, comprehensively useful, highly scalable and attractively priced. By this modern definition of cloud computing, System z has been an internalized cloud for decades and has found to have all the features to make it a natural Cloud Platform. The power of the mainframe's software and hardware virtualization, its shared resources architecture, its real and virtual memory controls, its in-memory internal communications structure, its specialty engines, its energy efficiency and its accommodation of Linux and Java natively are all cloud-relevant, and enable IBM System z machine to be a natural zCloud.

This article looks at all the cloud relevant features of IBM System z machines in detail.

Requirements
Any cloud system has to meet four basic requirements:

• Scalability involves the ability to grow large while functionality remains undiminished.
• Resilience is the ability to keep going when infrastructure elements fail.
• Elasticity is the ability to add resources to support a service without disruption of operations
• Finally, a cloud must support Security requirements for applications

Let's have a look at each of these requirements in detail with respect to System z machines

Scalability
IBM System z virtualization is a 40 year old technology.  Virtualization is delivered both at hardware and software level.  All System z models come with Processor Resource/System Manager  (PR/SM), the type 1 hypervisor that enables logical partitions (LPAR) to share system resources. PR/SM provides the ability to divide system resources into isolated logical partitions. Each logical partition operates like an independent system running its own operating environment.  This hardware level virtualization capability enables running thousands of virtual guest operating systems on a single Logical Partition. z/VM is the virtualization program that controls and distributes system resources so that many virtual machines can share the same physical resources.  With the help of zVM software and logical partitioning of hardware, a single mainframe can run more than thousands of operating systems and the The value realized at the infrastructure level is then permeated into PaaS and SaaS.

Massive virtualization enables near linear system scalability and system capacity can be plugged into existing and running systems. Here is a comparison of how IBM system z meets the scalability requirements compared to x86 servers.

Resilience
The System z product line is designed to offer fault tolerance to reduce single point of failure(SPOF).  System z and its associated software have evolved to the point that customers often experience months or even years of system availability between system downtimes. System z provides fault tolerance for all of its key components. This includes not just the CPs, memory or I/O, but also the timing oscillator card, power supply, channel paths and others.  Quick retargeting of spare instances of application elements, facilitated by virtualization ensures a longer period of Mean time between failure(MTBF).

IBM Mainframe parallel sysplex cluster contains multisystem data  and resource sharing technology and with this technology systems can harness the power of up to 32 z systems. In a parallel sysplex structure, every server has access to all data resources and every "cloned" application can run on every server. A  Globally Dispersed Parallel Sysplex(GDPS) ensures near-continuous availability and disaster recovery capability.

Elasticity
As mentioned in previous sections of this article, virtualization and resource allocation and coordination are built into the platform.  System z's Shared everything enables less components and a more simplistic IT foundation.  It supports capacity upgrade  on demand (CUoD) and on/Off Capacity on demand(on/off CoD) that is transparent to end users.

Capacity Upgrade on Demand (CUoD) allows for the non disruptive addition of central processor capacity.  CUoD can quickly add processor capacity up to the maximum number of available inactive engines.

On/Off CoD enables you to rent hardware capacity by the day and  can turn on/off processing units or Integrated Facilities from your original configuration.   You need to pay only for the days the processing units or Integrated Facilities are turned on.

Security
System z provides highly secure environment for the applications and operating systems.  Every component in a System z box operate in full isolation for security and recoverability. Morevoer, each of the components are integrated through memory-to-memory speed hipersockets (In-memory TCP/IP network) reducing intrusion points to minimum.  The z/OS intrusion detection system(IDS) uses policy-based - rather than signature-based - identification with capabilities for detecting and preventing not only known attacks, but also new attacks for which there are no developed attack signatures.

zSeries hardware partitioning was the first product of its kind to be awarded EAL5 (Evaluation Assurance Level) international common criteria security certification. The cryptographic co-processor does encryption   in hardware, reducing the performance penalty.

Overall System z Operational efficiency can be summarized as shown below:

TCO Analysis
Finally, let's look at a TCO analysis conducted by IBM to compare various cloud options. IBM has released the results of this TCO study comparing cost of five configurations given below for running 100 Linux images over five years.

• Buy stand-alone x86 servers (running one image/workload on each)
• Rent Amazon EC2 instances (running one image/workload on each)
• Buy large x86 servers and provision virtual servers using an x86 hypervisor (private cloud)
• Upgrade an existing z10 EC machine and provision virtual servers using z/VM (private cloud)
• Buy a new z10BC machine and provision virtual servers using z/VM (private cloud)

As per this study, Private cloud implementations built around larger virtualized System z servers can be up to 77% less expensive than public cloud options over a five year period and around 81% less than a distributed stand-alone server approach. Amazon EC2 based public cloud is expensive due to several factors like platform running charges for 24-7 operation and administration cost of each running application instance.

Summary
While meeting the basic requirements of a cloud platform, System z also reduces complexity with centralized management of networks and resources.  IBM Tivoli service automation manager-based resource provisioning and monitoring ensures an extremely cost-effective and scalable platform to fullfil these elastic computing needs. System z-based cloud systems have built in elasticity for just-in-time capacity supporting massive scale of the order of +900k users with TBs of data.  The virtualization and Share everything architecture of System z machines enables 100% system utilization without degradation in performance.  Hypersockets-based internal connectivity helps in scaling up inside the box, thus reducing the space requirements and electricity demands by 25% as compared to distributed platforms. This also leads to less resource requirements to support more workload resulting greater ROI for IT Projects.

References

• IBM System z Solution Edition for Cloud Computing : http://goo.gl/LgKM5
• Private Cloud TCO WhitePaper : http://goo.gl/JcVEu
• Deploying a Cloud on System z : http://goo.gl/ldGNZ