Admin Alert: Upgrading a 550 to a 520 with V5R4?

January 6, 2010 Joe Hertvik

On December 8, 2009, IBM made a little noticed announcement that opens up its 4.7 GHz two- and four-core Power i 520 systems to additional organizations and users. When originally announced, these servers were only available with i 6.1 support. Now organizations running the i5/OS V5R4 operating system can take advantage of these lower cost/higher capability machines. Here’s what happened and why it could be significant for your upgrade plans.

What IBM Announced

As originally released, IBM’s Power i 8203-E4A 520 two-core and four-core 4.7 GHz servers were limited to only running the i 6.1 operating system. They were not offered to i5/OS V5R4 users. With the December 8th announcement, IBM added support for running the i5/OS V5R4 operating system on these machines, which now allows organizations to consider using a 520 for an upgrade or a new purchase. IBM added support for running V5R4M5 on 8203-E4A machines to its configuration software in mid-December, and Big Blue is now shipping these machines to V5R4M5 customers.

This change was apparently spurred by two developments in the Power i world. First, IBM withdrew its four-core 4.2 GHz 520 machine from marketing as of October 2009. This left a hole in Big Blue’s 520 product line, cutting off some upgrade options for V5R4 customers with one-core and two-core 4.2 GHz 520s. Second, IBM recently extended marketing for i5/OS V5R4 through January 11, 2011, and technical support for the operating system should still be available through 2012. This probably made Big Blue more comfortable with supporting these machines for back-level operating system customers, even as it begins to issue a newer version of the operating system this year.

And of course, there’s customer demand. A lot of shops just aren’t ready to upgrade to i 6.1 along with their hardware upgrades, and Big Blue may have just needed to continue servicing customers who need a four-core 520 machine.

In order to use this support, customers have to run V5R4M5 on the 8203-E4A machines and certain PTFs have to be applied. There are also some unspecified I/O features on the 520 that require the i operating system 6.1, so certain features may not be available when running V5R4M5 on these machines (check with your business partners for more information).

Also note that these 520 machines are capped at four processors. The number of processors cannot be increased past four as they can with some Power i 550 models.

Upgrading a 550 to a 520????

With this announcement, it’s worth looking at the two-core or four-core 520 8203-E4A machines for an upgrade or a new purchase, even if your shop is currently running a System i 550 machine. Here’s why:

The 520s sell at a lower price than many of the 550 machines. With the 4.7 GHz processors, the 520s have comparable or in some cases greater power than the 550 boxes that are still selling with 4.2 GHz processors. Check with your business partner for exact price differences and 550 comparison models.
IBM hardware and software maintenance for 520 class machines is cheaper than it is for the 550 machines. This can bring down your out-of-pocket expenses when buying the machine outright, or it can bring down your monthly leasing cost if you are including maintenance in your lease.
A 520 machine may be a perfect choice for a CBU upgrade or a new CBU machine replicating a 550 box. IMHO, the rule is that the CBU must provide comparable capacity during a switch-over situation. However if your CBU is a four-core 520 and your production machine is a four-core 550, there really is no downside to using the 520 for a CBU. Their commercial processing workloads (CPWs) will be comparable. The CBU is a replacement machine and in most cases will only be pressed into service in a disaster. If the CBU has slightly less processing capability than the production box (say the production box is a 550 with five processors activated while the CBU has four processors), it definitely won’t matter when the CBU is replicating data from the production box. During an emergency switch-over where the CBU is impersonating the production box, it may not matter if you’re running four processors on the CBU to five on the production box because workload may also be reduced during this time. While configuring mixed 550 production-520 CBU environments is an individual organizational decision, many shops will be able to easily function with a four-core 520 machine as their CBU.
A 520 machine is in a P10 processor group (P-group) while a 550 machine is in the P20 P-group. In addition to affecting your IBM hardware and software maintenance, purchasing a 520 may also affect your third-party software licensing and maintenance costs. It used to be common practice for third-party software companies to price software and annual maintenance according to P-group. That is, you paid less for software running on a P-10 machine than you did for software running on a P-20 machine. However, with Moore’s Law continually doubling computing power about every two years, many AS/400, iSeries, and System i customers found themselves downsizing their P-groups during an upgrade cycle while increasing their computing power. The third-party vendors noticed this trend and many of them changed their pricing structures away from P-group pricing to pricing based on CPW or another scheme that still tied software costs to performance capacity. However, some vendors did not migrate away from P-group pricing. If you’re still running third-party software that is priced according to P-group, replacing a 550 with a 520 or buying a new 520 instead of a 550 could reduce your third-party software costs.

The Downsides

As mentioned before, these Power i 520 boxes are capped at four processors. There is no defined upgrade path today for a four-core 8203-E4A 520 machine. If you buy one of these machines and need more processing power, your only current alternative will be to buy a more powerful machine and swap it in for your current machine. This may or may not be a big deal depending on your organization’s financial situation, depreciation schedule, or leasing situation. It’s difficult to predict the future and IBM may or may not define an upgrade path in the next few years, but you should be aware of this limitation if you buy one of these machines in lieu of a 550 box that can be upgraded past four processors.

However, if you’re running i5/OS V5R4 and your upgrade needs fit well within the capabilities of the 8203-E4A (say you’re currently running three 550 processors on the machine that you need to upgrade or you’re looking at the 8203-E4A as a CBU purchase or upgrade), these 520s may fit rather nicely into both your processing needs and your budget.

Regardless of what your upgrade plans are, with knowledge comes options. And because of the December 8th announcement, there is now another option on the table for V5R4 520, 550, and CBU customers looking to upgrade in 2010.

The i 7.1s Have It; i5/OS V5R4 Extended

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