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Mirrors generating most traffic in 2016

It seems I haven’t posted the traditional annual mirror stats for 2016 yet. Well, lets fix that: Here are the most used mirrors on ftp.fau.de in 2016:

Rank Mirror Traffic 2016 in TB Rank/Traffic 2015 (for comparison)
1 qtproject (Qt Toolkit) 264 1 / 199
2 kiwix (offline Wikipedia) 262 2 / 179
3 osmc (Open Source Media Center) 172 – / 35
4 opensuse 145 4 / 139
5 mint 134 3 / 179
6 eclipse 131 6 / 97
7 fedora 115 5 / 100
8 cdn.media.ccc.de (Talk recordings from CCC conferences) 91 7 / 83
9 ctan (comprehensive TEX archive network) 76 8 / 63
10 tdf (The Document Foundation – LibreOffice) 58 9 / 48

Comparing this list to last year, the first thing one notices is the new entry on rank 3: OSMC generates a steady amount of traffic, with visible peaks whenever they do a release. They were not in the 2015 top ten because we only started mirroring it in Q4 of 2015.

Linux mint dropped from rank 3 last year to rank 5 this year, with much less traffic than last year. And that is despite a slightly different counting that should actually have increased their numbers: We are now summing up the two parts of the mirror, the ISOs and the packages. Not because we want to do that, but for technical reasons – we cannot always distinguish between the two in the stats, and not summing them up would make the stats even more wrong. Now judging from the stats, we must have been dropped from their mirror list for ISO downloads around June of 2016. From there to the end of the year, almost no requests for the Mint ISOs have hit our server. As to why we were dropped, we haven’t got the slightest clue – we got no notification about the removal. We did get a notice about being readded at the beginning of 2017 though.

Last years rank 10, videolan, dropped off the list – it would be on rank 13 this year.

Rank 1 and 2, Qt and kiwix, are really close head to head.

For all other mirrors, they swapped positions here and there, and all of them generated a little more traffic than the year before, but there were no big changes.

Lets take a look at IPv6 traffic only:

Rank Mirror IPv6 Traffic 2016 in TB Rank/Traffic 2015 (for comparison)
1 kiwix (offline Wikipedia) 34.6 3 / 14.5
2 cdn.media.ccc.de (Talk recordings from CCC conferences) 27.6 2 / 15.2
3 mint 20.8 1 / 22.6
4 qtproject (Qt Toolkit) 19.1 5 / 11.5
5 opensuse 18.4 6 / 10.8
6 debian 17.3 7 / 9.3
7 fedora 13.0 4 / 11.5
8 pclinuxos 12.9 – / 0.7
9 ubuntu 12.6 – / 3.2
10 tdf (The Document Foundation – LibreOffice) 12.3 8 / 8.1

With the exception of Linux Mint, where I’ve already explained the reason above, all mirrors had more IPv6 traffic, sometimes significantly more.

This is also visible in the total IPv6 traffic over all mirros: 13.68% of all traffic in 2016 was IPv6, up from 10.54% in 2015.

There are still huge differences in the IPv6 traffic share between the different projects mirrored, and most of the time it isn’t really clear why. One example where it is clear though is cygwin, with an IPv6 share of pretty much 0%: They use a setup-tool that downloads individual packages from the mirrors, and it seems this tool only does IPv4.

Evaluating Project Mirroring by Cost vs. Profit

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. 🙂

Mirrors generating most traffic in 2015

Here are the most used mirrors in 2015:

Rank Mirror Traffic 2015 in TB Rank/Traffic 2014 (for comparison)
1 qtproject (Qt Toolkit) 199 1 / 172
2 kiwix 179 – / 0
3 mint/iso (Linux Mint ISOs) 177 10 / 31
4 opensuse 139 2 / 106
5 fedora 100 6 / 44
6 eclipse 97 4 / 86
7 cdn.media.ccc.de (Talk recordings from CCC conferences) 83 8 / 32
8 ctan (comprehensive TEX archive network) 63 7 / 40
9 tdf (The Document Foundation – LibreOffice) 48 5 / 48
10 videolan 40 3 / 88

Kiwix on rank 2 has only been mirrored since March 2015, so it generated that amount of traffic in only 9 and a half months – it might well take over the top spot next year. The Ubuntu release ISOs dropped out of the Top 10 for IPv4. As is to be expected, the CCC conference recordings generate extremely peaky traffic after CCC events – setting a new record high with 11.3 TB in just one day on December 30 (after 32C3). It might even have made a little bit more, but unfortunately the webserver ran out of threads because someone apparently distributed web-torrent-files with 64 KB of chunksize.

The list is slightly different for IPv6.

Rank Mirror IPv6 Traffic 2015 in TB Rank/Traffic 2014 (for comparison)
1 mint/iso (Linux Mint ISOs) 22.1 10 / 3.1
2 cdn.media.ccc.de (Talk recordings from CCC conferences) 15.2 6 / 4.7
3 kiwix 14.5 – / 0.0
4 fedora 11.5 7 / 3.6
5 qtproject (Qt Toolkit) 11.5 1 / 9.1
6 opensuse 10.8 3 / 6.6
7 debian 9.3 5 / 5.4
8 tdf (The Document Foundation – LibreOffice) 8.1 8 / 3.4
9 eclipse 7.4 4 / 5.8
10 ubuntu-releases (Ubuntu CD Images) 6.0 9 / 3.2

IPv6 traffic is up – from 7.86% over all mirrors in 2014 to 10.54% in 2015. Absolute IPv6 traffic is also up in 2015 for all mirrors in the Top 10. The share of IPv6 traffic varies greatly between the mirrors.

Mirrors generating most traffic in 2014

While we publish daily stats for all of our mirrors at https://ftp.fau.de/cgi-bin/show-ftp-stats.cgi, there is currently no aggregation over a whole year. So here are the most used mirrors over the whole year:

Rank Mirror Traffic 2014 in TB
1 qtproject (Qt Toolkit) 172
2 opensuse 106
3 videolan 88
4 eclipse 86
5 tdf (The Document Foundation – LibreOffice) 48
6 fedora 44
7 ctan (comprehensive TEX archive network) 40
8 cdn.media.ccc.de (Talk recordings from CCC conferences) 32
9 ubuntu-releases (Ubuntu CD Images) 32
10 mint/iso (Linux Mint ISOs) 31

The list is slightly different for IPv6.

Rank Mirror IPv6 Traffic 2014 in TB
1 qtproject (Qt Toolkit) 9.1
2 videolan 7.4
3 opensuse 6.6
4 eclipse 5.8
5 debian 5.4
6 cdn.media.ccc.de (Talk recordings from CCC conferences) 4.7
7 fedora 3.6
8 tdf (The Document Foundation – LibreOffice) 3.4
9 ubuntu-releases (Ubuntu CD Images) 3.2
10 mint/iso (Linux Mint ISOs) 3.1

Still only a small fraction of the traffic is via IPv6, 7.86% over all mirrors and the whole year. CTAN for some reason drops out of the IPv6 list (it would be at #17), its Top10 slot is taken over by Debian (#16 in the total list) which has an unusually large IPv6 share. That large share can be attributed mostly to the local Computer Science Department which has large pools with IPv6 capable Debian machines.

experimental geo-ip-statistics

Since the beginning of September, we’ve been creating experimental GeoIP-statistics to see where the users of ftp.fau.de come from. We’re drawing nice maps from the results. You can find these stats from our general ftp statistics page – for days where GeoIP-stats are available, you will find a link to them at the bottom of the page. Here is an example:

geoipstats-ftp.fau.de-20141229-worldmap

As you can see, unsurprisingly most of our users come from Germany. Besides the map there is also a table that show the respective percentages per country – in the map above, Germany accounts for about 50 percent of all accesses. Note that is counting the number of bytes transferred, not the number of accesses.

We also have a map from the stats per Bundesland within Germany:

geoipstats-ftp.fau.de-20141229-germany

However, this second map is really mostly guesswork for a number of technical reasons:

  • To do the actual dirty mapping work, we’re using GeoLite data created by MaxMind, available from http://www.maxmind.com. This is a free-to-use version of their commercial GeoIP-database, and since they need to make a living from their database, the free version is of course less accurate than the version available to their paying customers. It just returns “unknown” for the Bundesland in roughly about 30% of all cases.
  • Due to technical limitations on our side, we’re currently using a rather dusted version of the geoip-mapping library, that for example still has problems mapping IPv6 addresses (although it works sometimes). The quality of the mappings should improve significantly after we update to their current version in the first half of 2015.
  • Our logs are normally anonymized, i.e. we do not store the full IP address of a client, but trim (at least) the last octet of an IPv4 IP. This further reduces mapping quality.

Still, we do think it is a rather interesting experiment. While we were expecting most of our users to be from Germany, we found the actual percentage suprisingly high – we had expected some more usage from other european countries.

More statistics

We have improved the publicly available statistics for our FTP server. You can now see how much traffic each individual mirror makes, and how much of the traffic was IPv6 vs. IPv4. The statistics are available at https://ftp.fau.de/cgi-bin/show-ftp-stats.cgi.

With this, you can see for example that the latest OpenSuSE 13.1 release had a quite significant impact on our FTP: The statistics for 19. November 2013 show that we distributed almost 9 TB for opensuse on that day, more than 5 times the traffic of all other mirrors combined.