Performance degradation on COMBO Cards

[Mendof]

How much degradation will have the ports of a Combo Card when all the ports are used? theory said minimal but customer states that he had seen as much as 40%.

[Olivier Masse]

IMHO, pushing all that data at the same time on all your ports would be unusual, you'll need a lot of CPUs, but of course that depends on your workloads. Mine never push these cards to their limits.

Now let's see.. let's take an average entry-level server such as a rx4640, it has 2 non-shared 133Mhz slots rated at 1GB/s. Assuming that's gigabytes, it then equals to 8Gb/s.

A full combo card will have 2*2Gb/s and 2*1Gb/s ports. That's a sum of 6Gb/s. So assuming the card itself can handle this load, it's enough.

Hope this helps

[Bill Hassell]

COMBO cards? Could you be more specific? Are you talking about SCSI+Centronics combo, or SCSI+console+LAN core combo, or perhaps one of a large number of multi-port LAN cards? Oh, and I am assuming this is a question for HP-UX and not a PC. And assuming this is a multi-port LAN card, there are very different designs on different cards and those designs place very different driver loads on the CPU. Need more details...

[Mendof]

I´m talking about that cards that has embeded FC and Ethernet Ports. Now the customer is using the LAN ports and needs use the FC port to attach a new array.

[Mendof]

Thx for your feedback

[rick jones]

Degredation compared to what precisely?

Gigabit Ethernet and FC are full-duplex, which means a pair of 2Gb FC's are 8Gb themselves, plus another 4Gb/s for a pair of full-duplex Gigabit Ethernet interfaces. So, that is 12 Gbit/s of "theoretical" bandwidth, _ignoring_ things like protocol headers and limitations of the bridge chips which must be used to make a combo card.

A PCI-X 133 MHz slot is capped at 7.X Gbit/s total. Not all slots are that fast even. Of course, the newest servers offer some 266 MHz I/O slots (rx2660, rx3600, rx6600 and the sx2000-based systems).

Also, not all combo cards run their "downstream" bus at 133 MHz. Some have to run at only 100 MHz or perhaps less. That depends on the specific card I suspect.

There are I believe some writeups for HP-UX and combo cards on docs.hp.com. Some of them have used netperf, which makes that one possible search term.