System i5s Go IOP-Less with i5/OS V5R4
February 13, 2006 Timothy Prickett Morgan
As IBM had promised it would do, the company is putting more and more intelligence inside the I/O adapters (IOAs) inside the iSeries line, so much so that it can actually begin to remove the I/O processors (IOPs) from the iSeries architecture.
IBM wants to do this for two reasons. First, it simplifies the architecture of the iSeries and allows it to have fewer components, which in theory will make it more reliable. Fewer parts mean fewer failures. Second, by taking the IOPs out of the equation, IBM can remove some of the cost out of the iSeries configuration and move the iSeries to more common I/O peripheral cards, such PCI-X cards it sells in its pSeries and xSeries products. When IBM gets a card to span three product lines, it can get better volume pricing from card suppliers (which should further reduce its costs) and also simplify its own technical support operations (which also helps lower costs in the long run).
While you can keep using IOPs on prior generations of AS/400 and iSeries hardware running i5/OS V5R4, if you choose i5/OS V5R4 on the new System i5 machines launched two weeks ago, you can plug in IOA peripheral cards in the systems, towers, and drawers in the i5 520, 550, and 570 servers and not mess with IOPs. Switchable iASPs and IOP-less disk arrays require V5R4; the V5R3M5 sub-release will not support these two features. One caveat: IOP-less operations are not, in general, supported with i5/OS V5R3, not even the V5R3M5 sub-release that was put out last year, but the exception is that you can go IOP-less on the i5 520 Power5-based machine running V5R3M5.
Of note, the new feature 5737 and feature 5766 PCI-X disk controller doubles the write cache of the feature 5703 controller to 90 MB, and now adds support for RAID 6 data protection. With RAID 6, you can designate an active hot spare disk in a RAID 5 array. This disk controller, which does not require an IOP, costs $1,999.