Microsoft sued over alleged Xbox 360 glitch 6741

In comp.os.linux.advocacy, Roy Culley wrote on Fri, 9 Dec 2005 00:46:43 +0100

A valid comparison, in some cases, but 'twere best it honestly done.

suggests that all z9 models have a footprint of 2.49 m^2 and a height of 1.941 m. A rack, at least according to www.racksolutions.com, can be various heights and depths; I'll buttume Dell depth (which is the deepest). A 44U rack would have height 84" or 2.134 m. Floor dimensions appear to be 31.5" depth by 23" width, or .4674 m^2. This means that dimension-wise a z9 has a little more than 5 fullrack-equivalents, floor-space wise, for 220 1U units total.

Now, to populate those racks:

buttuming each of these 1U slots is a PowerEdge 1850 ( dualsocket dualcore), and fully installed with memory (16 GB each, though for some reason the config page only allows 12 GB), one gets a total "clock speed" of 1.671 THz and a total memory usage of 2.64 TB. (These are admittedly very crude measurements.) One also gets a total power consumption of 121 kW.

(One slightly odd side note: the power consumption is a max rating. Presumably an idle system consumes far less, though memory refresh guarantees it's nonzero, and in my Kayak for some reason the main fan (an oversize affair in the back of the unit) ejects cooler air than the power supply fan. Whether that's true for the power supply in Dell's PowerEdge, I for one don't know; I find it slightly peculiar. Of course the Kayak is slightly peculiar; most other systems I've seen just eject all the heat through the power supply -- and said power supply, at least in a tower unit, is mounted as high as possible.)

The mainframe specs for an S54 are 512 GB RAM max, 18.3 kW. Not nearly as hungry -- or as beefy memorywise. But then the topology's different, and one might consider that an equivalent size of PowerEdges -- 43 1U units -- would require 23.7 kW of power (max), and would be unable to have a single program access all of that RAM at once, barring slightly unusual OS solutions. Score one for IBM.

However, now one has to consider the following metrics, in the design of a solution that meets an enterprise's needs.

1 Floor space. 2 Heat load (which for now I'm expressing in kW, but IBM gives equivalent figures in KBTU-hr as well, for HVAC designers presumably) 3 Network capacity. 4 RAM. 5 Disk space.

Furthermore, from what little I know about mainframes, there's *nothing in the mainframe* for persistent storage (except maybe a small unit that handles OS and booting); that's all handled by an external disk array. Therefore both the 18.3 kw and the 121 kW are extremely misleading as most 1U rack servers have an internal disk drive, which will sit mostly idle unless the unit is paging itself to rest -- an unlikely happenstance for a lightly loaded system with 12 GB RAM, but a possible if not probable occurrence with a busy webfarm.

Ideally, the metrics above (plus whatever additional ones are required) would be fed into a linear programming model, to optimize revenue, or at least I-O throughput, which I have no data on at present. (A bit odd since I was able to do the comparison with an earlier model -- the z390 -- with such metrics. I'll have to exhume that post from Google at some point.)

And then there's the S-W licensing costs. Scuttlebutt suggests IBM plays some weird games here for the underlayer, which is called z-VM. Linux runs on top of this underlayer (the phrasing at IBM's website says "Linux as z-VM guest"). How much does that underlayer cost? I've heard $50K, but that's a wild guess.

I've also not mentioned switches and such. Presumably in the rackmount these are 2U units, one per rack, each with 65 plugs (one for the upfeed). That bumps the actual CPUs down to 210 units.

And of course one can play games with the final licensing costs. For the Poweredges: 440 or 880 CALs appear to be required. (I could be wrong but if there are 2 CPUs per unit, and 2 cores per CPU, how is that charged?) Win2003 Server retails at $800 per; therefore $352,000 for the OS alone. IBM takes one license for Linux -- and it's free, if one chooses something like Gentoo. (That would be an interesting but rather unlikely solution. IBM offers RH Enterprise and SuSE. Unknown whether IBM can harbor multiple guests, and whether such multiple guests are akin to dualbooting or multiple VmWare-like processes, one per guest.)

But given all of the rest of the above, that OS cost is obviously an extremely misleading comparison, and only a part of the entire picture -- a fairly small part.

I should note that a 12 GB RAM dual 3.8 GHz Xeon will set one back $13,517 (this according to Dell's "Customize it" page), which means those 220 units will cost at least $3M -- and that's *before* one adds on things such as NICs, SCSI controllers, OS CALs, and hard drives. A 44U rack unit will set one back about $595,000, given this price. Presumably quanbreasty discounts are available, but if so I'd probably have to talk to a real live person... :-) I don't have $595,000 in my bank account anyway.

(I'm not sure which RAID-drive interface-drive solution is most effective in this config, and this is a hypothetical system I'm building anyway. Considering the flack given the hypothetical configuration given in one benchmark (4 100MB NICs vs. 1 GB NIC), the most probable thing to optimize for is CPU performance, and ensuring enough RAM is available for the problem. But I do note they offer SCSI drives in the PowerEdge.)

I have no idea how much an IBM z9 costs but it's probably not going to retail at Wal-Mart anytime soon... :-)

-- It's still legal to go .sigless.