People operate mirrors out of different reasons, this could be purely altruistic to support open source communities, or to reduce incoming traffic by providing local clients with an internal package source, or to tilt the in/out ratio of the internet uplink. What ever the reasons are, they are all associated with the usage of outbound traffic and local storage size, in addition to occupation of other hardware and administrative resources. We will consider traffic and storage requirements as the costs and outgoing traffic as the profit (to the general public or an organization) a mirror service provides.
Now looking around at what other mirror operators publish, it is very hard to find useful information to guide the mirror selection. Which means, that if you plan on hosting a new project, you have to rely on guesswork to estimate cost vs profit.
Although cost and profit are terms usually associated with currency based units, we will not estimate them using any such metric. We will consider Gigabytes as the unit for storage and traffic and therefore cost and profit.
By combining logged data from the ~50 mirrors we are currently hosting, we are in the position to quantify both cost and profit for each one of them. Be aware that the profit often depends on the geographic location, since many projects use a topology- and geography-aware load balancer like mirrorbrain.
Lets start of with the incoming traffic cost. The average number of GBs that need to be synced from the upstream mirror to ftp.fau.de per day:
| Mirror | Incoming Traffic |
|---|---|
| GB per day (average) | |
| kiwix | 16.63 |
| fedora | 4.29 |
| qtproject | 3.73 |
| debian | 2.65 |
| freebsd | 2.63 |
| ubuntu-ports | 2.52 |
| eclipse | 1.83 |
| cdn.media.ccc.de | 1.80 |
| deepin-cd | 1.54 |
| ubuntu | 1.51 |
| debian-cd | 1.28 |
| mageia | 1.18 |
| opensuse | 1.01 |
| macports | 0.95 |
| scientific | 0.94 |
| archlinux | 0.90 |
| trinity | 0.87 |
| macports/packages | 0.83 |
| netbsd | 0.81 |
| turnkeylinux | 0.75 |
| fosdem | 0.67 |
| gentoo | 0.64 |
| deepin | 0.45 |
| centos | 0.32 |
| xbmc | 0.27 |
| epel | 0.27 |
| packman | 0.27 |
| apache | 0.21 |
| openvz | 0.20 |
| osmc | 0.19 |
| mint | 0.19 |
| tdf | 0.16 |
| mint/iso | 0.16 |
| macports/distfiles | 0.12 |
| pclinuxos | 0.09 |
| openelec | 0.07 |
| opensource-dvd | 0.07 |
| ubuntu-releases | 0.05 |
| raspbmc | 0.05 |
| ripe.net | 0.05 |
| gnome | 0.03 |
| debian-backports | 0.03 |
| videolan | 0.02 |
| ctan | 0.02 |
| mint/packages | 0.02 |
| opencsw | 0.02 |
| CCC | 0.02 |
| knoppix-dvd | 0.01 |
| aminet | 0.01 |
| gimp | 0.01 |
| knoppix | 0.00 |
| grml | 0.00 |
| aptosid | 0.00 |
| mint/lmde-packages | 0.00 |
| gentoo-portage | 0.00 |
| macports/release | 0.00 |
| macports/trunk | 0.00 |
| putty | 0.00 |
| libreelec | n/a |
We calculated this by summing up all positive changes in mirror size, which is calculated and logged on a daily basis. Since we sync up to hourly, files that get synced and deleted within a day are not covered, nor are files that change.
How about storage costs? Since most mirrors stay around the same size, with a slight increase taking the average size works for most. But some have a tendency to constantly increase (or even decrease), this won’t be correct in all cases.
| Mirror | Storage Increment | Total Storage | Total Storage |
|---|---|---|---|
| GB per day (average) | GB (maximum) | GB (average) | |
| kiwix | 4.19 | 5690 | 3977 |
| cdn.media.ccc.de | 1.75 | 3189 | 2338 |
| scientific | 0.82 | 1602 | 1328 |
| fedora | 0.88 | 1712 | 1304 |
| ubuntu-ports | 1.22 | 1214 | 1153 |
| debian | 0.44 | 1347 | 1078 |
| CCC | 0.02 | 1073 | 1073 |
| mageia | 0.65 | 1139 | 890 |
| ubuntu | 0.20 | 916 | 773 |
| mint | -0.37 | 873 | 652 |
| eclipse | 0.43 | 824 | 630 |
| macports | 0.11 | 727 | 593 |
| freebsd | -1.12 | 1224 | 579 |
| qtproject | 0.59 | 731 | 517 |
| turnkeylinux | 0.34 | 724 | 517 |
| opensuse | 0.28 | 552 | 441 |
| mint/lmde-packages | -0.44 | 671 | 440 |
| macports/packages | 0.19 | 576 | 399 |
| fosdem | 0.57 | 394 | 370 |
| netbsd | -0.13 | 467 | 368 |
| gentoo | 0.07 | 329 | 288 |
| debian-cd | -0.05 | 679 | 280 |
| macports/distfiles | -0.08 | 258 | 193 |
| mint/iso | 0.06 | 206 | 190 |
| gnome | 0.03 | 175 | 174 |
| archlinux | -0.08 | 532 | 160 |
| trinity | 0.09 | 304 | 160 |
| epel | 0.06 | 155 | 117 |
| openvz | -0.26 | 172 | 105 |
| centos | 0.08 | 141 | 104 |
| pclinuxos | -0.03 | 97 | 93 |
| packman | 0.03 | 99 | 82 |
| ripe.net | 0.04 | 100 | 76 |
| apache | 0.07 | 117 | 69 |
| deepin | 0.25 | 257 | 67 |
| xbmc | 0.01 | 73 | 52 |
| opensource-dvd | 0.07 | 79 | 46 |
| aminet | 0.00 | 44 | 43 |
| tdf | 0.01 | 49 | 38 |
| deepin-cd | -0.01 | 583 | 36 |
| videolan | 0.02 | 37 | 31 |
| debian-backports | -0.04 | 34 | 30 |
| opencsw | 0.01 | 31 | 28 |
| ctan | 0.00 | 33 | 27 |
| ubuntu-releases | -0.01 | 41 | 25 |
| mint/packages | 0.01 | 30 | 22 |
| gimp | 0.01 | 22 | 19 |
| osmc | 0.09 | 30 | 16 |
| knoppix-dvd | 0.00 | 16 | 16 |
| openelec | 0.00 | 23 | 12 |
| grml | 0.00 | 12 | 12 |
| aptosid | 0.00 | 8 | 9 |
| libreelec | n/a | 6 | 6 |
| knoppix | 0.00 | 5 | 6 |
| raspbmc | 0.01 | 22 | 6 |
| gentoo-portage | 0.00 | 1 | 1 |
| macports/release | 0.00 | 0 | 0 |
| macports/trunk | 0.00 | 0 | 0 |
| putty | 0.00 | 0 | 0 |
Let’s have a look at the profit side of things, the outgoing traffic, and put that into relation with the costs. The scores on the right hands side, are calculated by dividing the average outgoing traffic by the average incoming traffic and by the average storage requirement:
| Mirror | Outgoing Traffic | Incoming Traffic | Storage Increment | Total Storage | Total Storage | Score Based on Traffic | Score Based on Storage |
|---|---|---|---|---|---|---|---|
| GB per day (average) | GB per day (average) | GB per day (average) | GB (maximum) | GB (average) | Outgoing vs Incoming | Outgoing vs avg. Storage | |
| osmc | 478.40 | 0.19 | 0.09 | 30 | 16 | 2518 | 29.90 |
| libreelec | 56.90 | n/a | n/a | 6 | 6 | ∞ | 9.48 |
| openelec | 93.70 | 0.07 | 0.00 | 23 | 12 | 1339 | 7.81 |
| videolan | 176.60 | 0.02 | 0.02 | 37 | 31 | 8830 | 5.70 |
| ctan | 138.80 | 0.02 | 0.00 | 33 | 27 | 6940 | 5.14 |
| ubuntu-releases | 91.80 | 0.05 | -0.01 | 41 | 25 | 1836 | 3.67 |
| tdf | 127.70 | 0.16 | 0.01 | 49 | 38 | 798 | 3.36 |
| knoppix | 13.40 | 0.00 | 0.00 | 5 | 6 | ∞ | 2.23 |
| mint/iso | 350.20 | 0.16 | 0.06 | 206 | 190 | 2189 | 1.84 |
| opensource-dvd | 48.80 | 0.07 | 0.07 | 79 | 46 | 697 | 1.06 |
| qtproject | 494.50 | 3.73 | 0.59 | 731 | 517 | 133 | 0.96 |
| grml | 10.10 | 0.00 | 0.00 | 12 | 12 | ∞ | 0.84 |
| opensuse | 365.00 | 1.01 | 0.28 | 552 | 441 | 361 | 0.83 |
| centos | 77.70 | 0.32 | 0.08 | 141 | 104 | 243 | 0.75 |
| xbmc | 35.60 | 0.27 | 0.01 | 73 | 52 | 132 | 0.68 |
| pclinuxos | 57.80 | 0.09 | -0.03 | 97 | 93 | 642 | 0.62 |
| deepin-cd | 21.00 | 1.54 | -0.01 | 583 | 36 | 14 | 0.58 |
| knoppix-dvd | 9.00 | 0.01 | 0.00 | 16 | 16 | 900 | 0.56 |
| epel | 57.10 | 0.27 | 0.06 | 155 | 117 | 211 | 0.49 |
| packman | 31.70 | 0.27 | 0.03 | 99 | 82 | 117 | 0.39 |
| eclipse | 238.90 | 1.83 | 0.43 | 824 | 630 | 131 | 0.38 |
| mint/packages | 6.90 | 0.02 | 0.01 | 30 | 22 | 345 | 0.31 |
| archlinux | 28.90 | 0.90 | -0.08 | 532 | 160 | 32 | 0.18 |
| macports/packages | 66.40 | 0.83 | 0.19 | 576 | 399 | 80 | 0.17 |
| fedora | 195.00 | 4.29 | 0.88 | 1712 | 1304 | 45 | 0.15 |
| kiwix | 560.40 | 16.63 | 4.19 | 5690 | 3977 | 34 | 0.14 |
| raspbmc | 0.80 | 0.05 | 0.01 | 22 | 6 | 16 | 0.13 |
| aptosid | 1.00 | 0.00 | 0.00 | 8 | 9 | ∞ | 0.11 |
| aminet | 4.70 | 0.01 | 0.00 | 44 | 43 | 470 | 0.11 |
| macports/distfiles | 18.90 | 0.12 | -0.08 | 258 | 193 | 158 | 0.10 |
| gentoo | 26.70 | 0.64 | 0.07 | 329 | 288 | 42 | 0.09 |
| turnkeylinux | 46.10 | 0.75 | 0.34 | 724 | 517 | 61 | 0.09 |
| cdn.media.ccc.de | 185.50 | 1.80 | 1.75 | 3189 | 2338 | 103 | 0.08 |
| opencsw | 2.20 | 0.02 | 0.01 | 31 | 28 | 110 | 0.08 |
| mageia | 62.10 | 1.18 | 0.65 | 1139 | 890 | 53 | 0.07 |
| apache | 4.40 | 0.21 | 0.07 | 117 | 69 | 21 | 0.06 |
| fosdem | 22.70 | 0.67 | 0.57 | 394 | 370 | 34 | 0.06 |
| deepin | 3.60 | 0.45 | 0.25 | 257 | 67 | 8 | 0.05 |
| ubuntu | 41.00 | 1.51 | 0.20 | 916 | 773 | 27 | 0.05 |
| debian | 57.10 | 2.65 | 0.44 | 1347 | 1078 | 22 | 0.05 |
| gimp | 0.90 | 0.01 | 0.01 | 22 | 19 | 90 | 0.05 |
| debian-cd | 12.70 | 1.28 | -0.05 | 679 | 280 | 10 | 0.05 |
| CCC | 25.80 | 0.02 | 0.02 | 1073 | 1073 | 1290 | 0.02 |
| gnome | 3.80 | 0.03 | 0.03 | 175 | 174 | 127 | 0.02 |
| trinity | 2.90 | 0.87 | 0.09 | 304 | 160 | 3 | 0.02 |
| freebsd | 8.20 | 2.63 | -1.12 | 1224 | 579 | 3 | 0.01 |
| openvz | 1.00 | 0.20 | -0.26 | 172 | 105 | 5 | 0.01 |
| macports | 4.80 | 0.95 | 0.11 | 727 | 593 | 5 | 0.01 |
| scientific | 9.30 | 0.94 | 0.82 | 1602 | 1328 | 10 | 0.01 |
| ripe.net | 0.40 | 0.05 | 0.04 | 100 | 76 | 8 | 0.01 |
| netbsd | 1.70 | 0.81 | -0.13 | 467 | 368 | 2 | 0.00 |
| ubuntu-ports | 4.70 | 2.52 | 1.22 | 1214 | 1153 | 2 | 0.00 |
| debian-backports | 0.10 | 0.03 | -0.04 | 34 | 30 | 3 | 0.00 |
| mint | 0.80 | 0.19 | -0.37 | 873 | 652 | 4 | 0.00 |
| mint/lmde-packages | 0.30 | 0.00 | -0.44 | 671 | 440 | ∞ | 0.00 |
| gentoo-portage | 0.00 | 0.00 | 0.00 | 1 | 1 | ∞ | 0.00 |
| macports/release | 0.00 | 0.00 | 0.00 | 0 | 0 | n/a | n/a |
| macports/trunk | 0.00 | 0.00 | 0.00 | 0 | 0 | n/a | n/a |
| putty | 0.00 | 0.00 | 0.00 | 0 | 0 | n/a | n/a |
What can we learn from this? Small projects can produce a lot of traffic (osmc), especially if they tend to have a small mirror network (libreelec) or a humongous user base (videolan). Big mirrors on the other hand, often produce a lot of traffic in an absolute sense (kiwix, cdn.media.ccc.de), but they are unable to compensate for their storage requirement. For example, the CCC media mirror would have to constantly saturate 2 Gbit/s to get the same traffic/storage ratio as videolan. Although we love outgoing traffic, thankfully they do not. 🙂