Re: Re: Re: An expandable, available dual is needed - perhaps more than a quad
Originally posted by AidenShaw
A quad needs twice the memory bandwidth of a dual, and to scale should also have at least twice the IO bandwidth. This makes a quad-capable box more expensive per CPU - especially if not fully populated. [BTW, you can have 3 processors as well, they don't have to be powers of two in most systems.]
For example, pricing 3 Dell single CPU systems - all with 1 2.8GHz Xeon, 1 GiB of RAM, and one 36 GB disk.
1U - $3,634 (PE1750 - dual capable, $4,033 with 2 CPUs)
2U - $4,025 (PE2650 - dual capable, $4,424 with 2 CPUs)
4U - $10,563 (PE6650 - quad capable, $25,562 with 4 CPUs)
You'll find the same price structure wherever you look - quads are big bucks! The "quad tax" is very large!
this is missleading.
A quad system in Apple's case would need a chipset that supported more HT-like links for more than two processors. Maybe they could add this logic fairly cheaply, maybe not.
A quad system doesn't automatically need double the bandwidth of a dual though. G5s have a lot of bandwidth already. It depends on what the server is doing really. Some applications could use as much bandwidth as possible, others wouldn't care so much... reasonably fast is usually better than a network connection between two dual nodes. The nice thing about the extensive use of HT is, it might not be that hard to double the bandwidth to the memory though. It probably wouldn't be a monumental task to move the memory controller to support 4way configs and then double the bandwidth to the main system hub.
There are a few things that would affect pricing of an Apple quad. Among them:
- R&D.. how much work to make a quad capable chipset... what are the volumes expected.. how long to get ROI on that R&D investment?
- physical components.. more CPUs, more of this and that
- extra engineering of the product. Quad servers are always going to be in mission critical roles. You need real redundant power supplies (our quad capable dells had 3 power supplies). Quads usually have quite a bit of internal disk space too (they often host databases). If you have to engineer in a lot of extra redundancy, more storage, faster (Ult320 RAID) storage I/O, and the like, you have higher costs.
- cost/demand curves. Enterprised EXPECT to pay more for quad processor machines. They will pay a premium for them too. If your cost for the hardware and R&D is $4000, and you sell them for $6000 which moves 1000 units a year... that's $2,000,000 per year in profit.
If you assume that people who NEED quad processor server will buy them even if they are expensive.. and you expect to sell only 750 units at $10,000 (same cost), you'll be looking at slightly higher per unit cost (R&D amoritized over fewer units) but you margin will be huge. You may be looking at a yearly profit more like $4,000,000 instead of $2,000,000.
Bottom line is, Apple will (to a good extent) charge what the market expects for a quad processor server at a certain performance/feature level.
If it's a bare, single PowerSupply cluster node it will be a lot cheaper than a full fledged SCSI based DB server, but it still won't be cheap because a) it will perform better than two dual processor servers when crunching data, and b) people expect to pay a good amount for quad servers.
... but just imagine what a quad 2.5 GHz could do. Just one on a fast backbone could be the hidden workhorse for Media developers, Code developers... It'd be impressive to see a dozen developers on GigE using xCode with a quad G5 hidden in the closet.
