With the announcement of V6R1, i5/OS is finally growing up. Packed with interesting technical improvements, this version marks the beginning of a new operating system released from its proprietary background, and that's the real news. Because of the fact that many constraints remain, V6R1 is not an unconditional release, but the improvement in status for i5/OS is remarkable. Among the changes that mark this transition are support for the generic JS22 blade, support for midrange storage such as the DS4700 and DS4800, generic I/O virtualization, and a complete revamping of the development tool and language support.

This is the first time in the operating system's history, going all the way back to CPF on the System/38 in 1978, that i5/OS support for the JS22 blade is available on a hardware model that is not System i (or its predecessors too numerous to name) specific. Despite that the hardware has become much more generic with the POWER processors and that you can technically run i5/OS as a partition under AIX, you had to order a System i box in the past if you wanted a system that just ran i5/OS.

The JS22 is not an irrelevant piece of hardware. With two processors, four cores, and 11,000 CPW, it has redefined the System i hardware landscape. It took a perfect storm of changes to make it happen. Because i5/OS still needed a service processor, the JS22 blade had to include one. Also, i5/OS's unique IOPs requirement had to go away or be finessed. You had to overcome load-source restrictions, console restrictions, and 520-byte disk-sector requirements (instead of the industry standard 512). It took years of work to slowly remove the restraints and, in the end, it required the addition of a brilliant piece of software, the virtual client support in i5/OS, to make it all possible. This support is implemented through the HMC and hypervisor for traditional System i hardware and through the Virtual Input/Output Server (VIOS) for blades.

A System i blade based on POWER processors has been a dream since IBM announced the blade center hardware. However, blades present some real challenges because they have no directly attached devices and very limited onboard disk. To make i5/OS work on a blade, the console, disk, Ethernet, optical, and tape must be virtual. LAN console capability in i5/OS solves the console problem, but the rest falls to the VIOS.

Originally announced as System p hardware to support AIX and Linux, VIOS was very well received. It provided a much higher level of virtualization than was available to i5/OS as a client. With V6R1, it now does the same for i5/OS. VIOS boots from the on-blade disk drive and runs in its own partition. A browser interface lets you configure the virtual resources and the other partitions. Thus, the blade is OS neutral and doesn't care if you run i5/OS, AIX, Linux, or any combination thereof.

If you have run partitions on i5/OS versions prior to V6R1, you know that you already have virtual I/O. You also know that it comes with severe restrictions. One is that you must have a dedicated IOP and boot drive for each partition. This is both expensive and restrictive. It limits your ability to quickly provision and deploy new partitions. With V6R1, this restriction is removed, and you can IPL from a virtual drive. Thus, if you have enough storage, you can quickly and painlessly implement new partitions for development, testing, or any other purpose without purchasing or configuring new hardware.

Another big storage constraint occurred in the past if you wanted to use external storage from a Storage Area Network (SAN). In such a case, you had to configure the storage to dedicate specific Logical Units (LUNs) in sizes that exactly matched supported internal drives to i5/OS. This was due partly to the System i's non-standard 520-byte sectors and partly to OS device-drive restrictions in i5/OS. As a result, System i external storage was supported only on IBM's largest and most expensive enterprise storage servers — DS8000 (previously known as "Shark") and DS6800.

VIOS does something that even the SAN Volume Controller (SVC) cannot do — it virtualizes this problem away. It hides both the LUN size and the sector size of the underlying storage system from i5/OS, letting you quickly, efficiently, and dynamically allocate storage to an i5/OS partition. This, in turn, facilitates support for midrange DS4700 and DS4800 storage systems that are less expensive than the 8000 series and more often found attached to blade centers.

Although VIOS is the most important indicator of i5/OS's emergence, it is not the only one. IBM is finally deprecating legacy development tools and languages in favor of current and emerging languages and the Eclipse-based Rational tool set. Mainstream JVMs and lightweight Web Application Server support are also indicators.

Yes, i5/OS is embarking on a new, exciting phase of its long and innovative life. Now that the operating system is growing up, shouldn't IBM give it a grown-up name?

Carson A. Soule is a System iNEWS technical editor and the CEO of CAS Severn, Inc., an IBM Premier Business Partner, in Laurel, Maryland. He is a frequent speaker at conferences and seminars worldwide.