When IBM announced new disk controllers and storage offerings for the iSeries last month, it also made important statements about how it will gradually eliminate older, proprietary technologies from future iSeries models. While the statements were made rather quietly, their content will have a significant impact on the upgrade and development plans of thousands of iSeries owners.
Among IBM's announcements, the ones that will have the greatest impact were several planning statements about support for networking and connectivity protocols. On the networking front, the company said that the current release of OS/400 (known as i5/OS or V5R3) and the next release will support the SNA, SDLC, X.25, and Frame Relay protocols. Beyond the next release, however, the company will discontinue support for these protocols. From a planning standpoint, this means that support within current OS/400 releases will probably end sometime during 2007. However, OS/400 will continue to support other protocols, including TCP/IP, Ethernet, PPP, asynch, bisynch, and APPN via IBM's Enterprise Extender product.
While OS/400 support for these protocols will continue for the next couple of years, IBM is immediately dropping support for the protocols in any new LAN and WAN adapters that it announces. This decision could have the greatest impact on iSeries shops that use remote 5250 workstations, as most remote 5250 controllers connect to the iSeries via SDLC or X.25. Customers who use the discontinued protocols and need adapters should source them from other vendors, buy used IBM adapters, or migrate to TCP/IP.
In addition, iSeries customers should start planning how they will migrate applications off the discontinued protocols. Many customers with X.25 and Frame Relay applications will likely retool them to run on Virtual Private Networks (VPNs) running over TCP/IP. When it comes to migrating SNA applications, one alternative will be to rewrite the code for IP-based networks. Another alternative will be to use Enterprise Extender to run SNA applications over TCP/IP using the APPN transport mechanism. Though few iSeries shops know about Enterprise Extender, the product is gaining traction at mainframe sites where IBM has offered the product for years. Enterprise Extender provides a way to run SNA applications over TCP/IP that is faster, more reliable, and more robust than the AnyNet facility currently available on OS/400. While Enterprise Extender is not currently available for the iSeries, IBM issued a statement of direction last October that it would provide the facility in a future OS/400 release. As such, Enterprise Extender should ship with OS/400 V5R4 sometime next year.
Farewell Twinax and Token-Ring?
In a related planning statement, IBM also declared that while new OS/400 releases will continue to support twinaxial and Token-Ring adapters, the company will stop selling such adapters in mid-2006. Since many terminals, printers, and PCs connect to the iSeries via these adapters, the statement presents some serious planning considerations to owners of these devices.
Among those considerations, the biggest one is what companies should do with their 5250 terminals. Because 5250 terminals rely on twinaxial connections, it may seem as if IBM is putting a stake through the heart of the trusty "green-screen." However, that is an overstatement. After 2006, customers will still be able to purchase used twinax adapters from IBM and new ones from other vendors. All twinax and Token-Ring adapters will continue to receive support in current OS/400 releases. Of course, IBM's departure from the market for these adapters will persuade some customers to migrate off twinax and Token-Ring to Ethernet-attached devices. However, many customers will maintain pools of these devices for years to come. Those customers will provide connectivity and peripheral vendors with steady though dwindling orders for twinax adapters, 5250 terminals, and other twinax-attached devices.
While iSeries owners will have the option to stick with their twinax devices, many of them will have to part with one piece of hardware: the disk drive that contains their OS/400 load source. At present, all OS/400 load sources can fit on 8 GB drives. However, according to another IBM planning statement, the next OS/400 release will be large enough to require a disk drive that is at least 17 GB. There is even a possibility that a future PTF could make OS/400 V5R3 too large to fit on an 8 GB drive. As such, customers who are running their load sources on 8 GB drives should plan to migrate to at least a 17 GB drive. Since the smallest drive that IBM currently sells is 35 GB, most customers will probably choose a 35 GB drive.
This decision may seem simple in theory, but it could be complicated in practice. Since customers should mirror their load source drives or put them in a RAID array, many customers may need to purchase two or three 35 GB drives. If their iSeries do not have enough empty disk slots to house the new drives, customers may have to remove older and smaller drives. In addition, if customers put the new 35 GB drives in the same auxiliary storage pool (ASP) as smaller disk drives, they could experience I/O performance problems. This could force some customers to put their 35 GB disks in a different ASP than their smaller drives. Moreover, some customers may find that they need new I/O adapters or disk controllers.
In short, deploying a larger load source could trigger a cascade of storage decisions for many customers. If you think your company could be one of those customers, I would advise you to talk with your IBM account manager or Business Partner about your options as soon as possible.
As you consider those options, you should also know that IBM has adopted a long-term strategy to move the iSeries to an architecture that has no I/O processors (IOPs). Over time, IBM will gradually distribute the functions of IOPs to the central processors and I/O adapters of new models. This does not mean that future iSeries models will not support IOPs; it only means that customers will have the option to migrate to an IOP-less architecture. That architecture should provide users with more open PCI slots and greater configuration flexibility. It should also allow IBM to build iSeries servers at a lower cost. Hopefully, the company will pass some of those savings on to customers.
As IBM implements its planning statements over the next several years, iSeries customers will need solid advice on their upgrade and migration options. While your company may eventually need "face time" with an IBM expert to sort through those options, you can learn a lot about them today by pointing your browser to the iSeries Upgrade Planning Web site. The site will give you the knowledge you need to ask the right questions when your next iSeries upgrade becomes a top priority.
Lee Kroon is a Senior Industry Analyst for Andrews Consulting Group, a firm that helps mid-sized companies manage business transformation through technology. You can reach him at