Original Post
It's not free to copy a file, especially over a network. It may look free because you buy the necessary resources in bulk, and without any planning for their use, but ultimately the necessary resources to enable a file copy have a real cost. So, can we feasible calculate this cost (irregardless of the purpose)? What is involved? Let's have a little thought experiment. 1.) the storage space for the live copy, the one from which all copying is done 2.) the storage space for the backups, to ensure you never lose the file 3.) the computer that does the copying, as a fraction of the amount of time that the copy takes over the total lifespan of the computer 4.) the electricity to run the processor for the copy operation 5.) the bandwidth to send the copy to the destination 6.) the domain name so that users can find your file to copy Let's say this file that we are copying is large, like a Linux distro. The Debian ISOs weigh in at 5GB (5,008,271,360 bytes = 5GB as hard drives are measured). I guess the easiest way to tally this all up would be to add up the yearly costs of everything and divide by the total number of downloads possible in one year. 1.) Here is a 300GB HDD for about $100, so about $0.33/GB. That means our distro is taking up $1.67 of HDD space. 2.) Here is a 25pk of dual layer DVDs for about $41, so about $0.61 a disc. Single layer DVDs at 4.7GB aren't big enough to store our ISOs, so we need dual layer DVDs. If we are burning just our distro, we'll use up 1 entire disc, though reallistically we would backup the entire contents of our HDD on multiple discs, allowing us to use the storage space more economically. As a fraction of the disk, it's $0.36. 3.) I'm going to be arbitrary and say $500 for the computer, sans the hard drive, since I already calculated that price. I'm going to assume we upgrade every year. 4.) This one is difficult for me, can someone check it? Residential Electricity Prices: A Consumer's Guide says $0.0955/kWh for electricity in my area. Say our computer draws 300W, with 365.25 days a year and 24 hours a day, that's about 2600 kWh and $251.14. 5.) Monthly fee for a 1yr contract on a private T1 line is about $795 with a one time $500 setup fee. A total cost of $10040. At 1.544 Mbps, it will take about (5GB/file * 1000MB/GB * 8MB/Mb / 1.544Mbps = 25906s/file) about 26000 seconds to download our file with full bandwidth usage, or 7 hours, 11 minutes, 47 seconds. (wait, does that seem right?). With 31556736 seconds in a year (60s/m * 60m/h * 24h/d * 365.25d/y = 31556736s/y), that means we can send this file 1218 times in one year. We need this number later. 6.) GoDaddy charges about $9 for 1 year of domain registration, for .com, .net, or .org.. (zeros used to line everything up). 00001.67 00000.36 00500.00 00251.14 10040.00 (bandwidth is a hog!) 00009.00 ======== 10802.17 / 1218 downloads per year = $8.87 per download. Or, about $1.77/GB. Of course, we have to add in our inefficiencies. We can't count on 100% bandwidth usage, either the server goes down, or the network goes out, or people just aren't downloading. The server going down will help us with our electricity bill, but ultimately is dwarfed by the money lost on inneficient bandwidth usage. With bandwidth, time is literally money, $0.02 a minute, $1.15 an hour, $27.49 a day. With the server down, the network out, or people not downloading the file 24/7, I could watch a counter tick away the money I'm losing. Anyone want to play along and see if they can improve these numbers?
