computing budgeting (fwd)

Date view Thread view Subject view Author view

From: Kragen Sitaker (
Date: Wed Sep 06 2000 - 16:29:02 PDT

Adam forced me to forward this to FoRK at the point of a very sharp pikachu horn.

<>       Kragen Sitaker     <>
Perilous to all of us are the devices of an art deeper than we ourselves
                -- Gandalf the Grey [J.R.R. Tolkien, "Lord of the Rings"]

---------- Forwarded message ---------- Date: Mon, 28 Aug 2000 03:15:41 -0400 (EDT) From: Kragen <> To: Subject: computing budgeting

Suppose we want to charge fairly for disk usage. You can get a 75GB disk now for $600; if you have six of these in two RAID-4's mirrored at different sites to provide 150GB of highly-reliable storage, it will cost you $3600. If we assume a nominal ROI of 3%, that means it costs you $108 per year. Irrelevantly tiny.

Disks seem to halve in price in about a year; if we use that as a seat-of-the-pants basis for depreciation, this setup depreciates $1800 per year, or about $150 per month. (If we assume it's really exponential, it's about $202 for the first month, but $1 per gigabyte is a nice round number.)

$1 per month per gigabyte isn't too bad. It works out to about 2 628 000 000 000 000 = 2.6e15 byte-seconds per dollar. Or 3e10 byte-days per dollar. Or 82 million byte-years per dollar.

How about memory? You can buy half an ECC PC133 gigabyte for $850 without any trouble, and it seems you can get it for as little as $550. (Specialized RAM --- HP NetServer or Compaq Proliant --- costs much more.) If we go with the $850 figure, and depreciate the same way as for the disks, we get about $100 per month per gigabyte of RAM. 2.6e13 byte-seconds per dollar.

CPU cycles? You can buy a motherboard with a 750MHz AMD K7 "Athlon" for a bit under $300. Assume the case is irrelevant to cost (it's cheap and doesn't depreciate very fast) and that the CPU and mobo depreciate exponentially, losing half their value within a year, just like everything else. Then you're spending $17 per month for this guy. It goes through 1 971 000 000 000 000 --- roughly 2e15 --- clock cycles in a month. That's 1.1e14 CPU cycles per dollar.

So the prices are: 2.6e15 byte-seconds of extremely reliable online storage per dollar 2.6e13 byte-seconds of high-quality RAM storage per dollar 1.1e14 CPU cycles per dollar

All of this is assuming that no system administration or transaction cost is needed, of course --- sysadmin costs typically double the real costs of computer systems, but depend heavily on the usage.

This is very promising. This means that, in an ideal market, if you can spend a penny per year on your share of shared computing resources, you could get today: - 824 454 bytes of disk space, or - 8 245 bytes of RAM (averaged), or - 34 880 CPU cycles per second (averaged)

What this says to me is that the traditional stuff timesharing setups used to charge people for is now all irrelevantly cheap for ordinary use. What costs money now is other stuff: face time with people, work in keeping the system running, time spent tracking down intruders and hitting them with baseball bats, rack space, and bandwidth. And hardware to interface with people.

If I were building a timesharing system today, I would expect that the majority of users would spend less than a dollar per year each for disk space, RAM, and CPU time. I'd still charge them, but I wouldn't bother to try to extract payment until the balance was over $10.

-- <> Kragen Sitaker <> Perilous to all of us are the devices of an art deeper than we ourselves possess. -- Gandalf the Grey [J.R.R. Tolkien, "Lord of the Rings"]

Date view Thread view Subject view Author view

This archive was generated by hypermail 2b29 : Wed Sep 06 2000 - 16:30:50 PDT