UNIX variants have continued to grow strongly in the market over the past 10 years, which is generally a good indicator of a strong future of continued development and support from major vendors (with the obvious exception of Oracle’s Solaris support!). IBM is now the leading vendor in the UNIX market*, and has strong roadmaps for:

• Linux, typically recommended for its x86-based servers
• AIX, offering tight integration with POWER servers for the larger enterprise.

One of the major benefits of staying with UNIX is that you continue to enjoy the benefits of reliability, scalability and high availability, combined with strong hardware and OS integration.

Some fairly obvious examples of hardware and OS integration are I/O device drivers, and memory and paging architectures, which you’d expect to be optimised by the combination of hardware and OS developers.

But beyond that, there are more specialised integration technologies that deliver real performance and scalability benefits on UNIX systems. As an example, we’ll look at the integration of the IBM POWER series servers and AIX. IBM develops its own chipset, the POWER chips, which are used in the POWER servers.

Incidentally, most people encounter these POWER chips in their everyday life without knowing it – the POWER chip is the heart of every Xbox, PS3 and Wii gaming console as well as many other electric goods (including fridges, cars, TVs etc). The widespread usage of the POWER chip, both inside and outside the IT industry, provides IBM with opportunity and funding for further research and development and improvement in their chipset technology. This ensures a steady roadmap a number of generations in the future, with predicable release schedules and architectural improvements.

IBM also:

• Develops the OS (AIX) that runs on the POWER series servers
• Packages and configures the servers for best performance
• Develops the hypervisor used for virtualisation
• Integrates the hypervisor into the server hardware

The complete control of every element of the solution allows IBM to continually optimise different elements of the solution, and their integration, to deliver best performance. This approach is clearly successful, with POWER/AIX benchmarks and reliability surveys showing that this combination constantly outperforms Solaris and others. For example, a Yankee Group Research study showed AIX as the most reliable server operating system, compared with HP-UX, Soloris, SuSE Linux, Red Hat Linux and Windows Server 2003.

A strong example of hardware and OS integration that delivers performance benefits is Active Memory Expansion, available on POWER7 systems, which allows the server to compress memory on-the-fly, providing the application with more memory than is physically allocated to it. For heavy transactional systems such as SAP, this can provide up to 100% more memory to the application without requiring additional physical memory.

Another example is the simultaneous multithreading supported by the POWER series chips. This allows multiple threads to execute concurrently on a single processor, and can lead to approximately a 30 percent improvement in throughput.

IBM also writes its own hypervisor, which runs directly on the system’s hardware. The hypervisor is responsible for the time slicing and dispatching for the partition workloads between processors. Hypervisors that run on hardware are known as a Type 1 hypervisors, while Type 2 hypervisors are software applications running under an operating system. Using a Type 1 hypervisor allows multiple operating systems to run concurrently on the same physical hardware, and also removes the system overheads associated with Type 2 hypervisors, automatically delivering better performance. Type 1 hypervisors are also better able to isolate individual partitions than Type 2 hypervisors, delivering increased security, higher uptime (by ensuring that problems in one partition do not affect other partitions) and stronger load balancing.

The PowerVM hypervisor developed for use with the POWER series servers further underpins AIX’s high performance with capabilities including:

• The ability to move processor, memory and I/O resources on the fly to balance load
• Reallocation of spare CPU cycles to a shared pool for access by virtual machines – this includes both addition and removal of CPU and memory cycles. The removal of resources is something that most Type 2 hypervisors struggle with, at present.

Choosing a hardware and OS combination from one vendor also simplifies your configuration and tuning options. IBM offers pre-configured servers based on workload: for example, one configuration for data analysis heavy workloads, and a different configuration for high volume transaction processing. This pre-configuration is a natural extension of the hardware and OS integration we’ve already discussed, and makes your life easier in terms of optimising performance of your business critical applications.

If you’re looking to move from Solaris, it’s time to take a look at the current breed of high performance, high availability and highly scalable UNIX variants, including AIX. Especially with virtualisation, it’s now possible to get more processing power and memory than ever for your money.

This is part of a series of blog posts that offers insights into critical points to consider as you plan the migration of your critical business systems from Solaris. The next post continues our exploration of the benefits of UNIX for your critical business systems.

* According to an IDC report summarised at http://www.ibm.com/developerworks/aix/library/au-unix40/

Synergy is an IBM Business Partner. Views expressed in this blog do not necessarily reflect those of IBM.