There are two places I go when I want to download Ubuntu installer images: cdimage.ubuntu.com and releases.ubuntu.com.

Both of these appear equally official: they are both subdomains of ubuntu.com, and the main Ubuntu website makes references to both for its download links. (http://www.ubuntu.com/download/alternative-downloads uses the former for its 'Network installer' download links, and the latter for its 'BitTorrent' download links, for example.)

If I visit http://releases.ubuntu.com/ and follow links for the current Ubuntu release, I reach a page that lists numerous links to desktop and server installer images. Likewise, if I visit http://cdimage.ubuntu.com/ and follow links in a similar manner, I get to another very similar page that also gives numerous links to desktop and server installer images. At the moment, these pages are:

(Following '14.04' links instead of 'trusty' leads to pages identical to the above, aside from their URLs.)

The language used on those two pages suggests that each page lists all of the available image files. For example, they each say "A full list of available files, including BitTorrent files, can be found below", and they each provide a wide variety of link types (.iso, .torrent, .metalink etc).

Neither page makes any reference to the other page's existence, and for a long time I thought that these were simply two different URLs serving essentially the same list of installer images.


Now that I look more closely I see that, despite appearances, the actual lists of files are almost entirely different. For the Trusty release, releases serves i386 and amd64 images, whilst the cdimage site serves PowerPC and Mac-friendly images. Even going back to the Precise release, when the architectures overlapped more, there are still installer images on each page that are not available from the other.

I've searched for explanations as to why the two sites are so disjoint, but have so far found none.

I assume that releases.ubuntu.com is intended to hold the more common installer images, whilst cdimage.ubuntu.com is intended to be a more comprehensive archive, given that it also hosts installers for the various spins such as Lubuntu, Xubuntu, etc.

However, this still doesn't explain some things:

  • Why is there no single page I can go to and see all available images? For example, if releases.ubuntu.com is reserved for the more popular images, why are these not also included in the (more comprehensive) list at cdimage.ubuntu.com?

  • If there's a good reason for keeping them separate, then why does neither page acknowledge the other as a complementary source of installer images?

  • Is there any historical reason for this split?

If anyone has any behind-the-scenes insight into this, I'd be interested to hear how things ended up this way.

  • Although I have no answer, thanks for pointing out the difference. I had only noticed it today and thought i386 had been abandoned. – 0xC0000022L Jul 28 '14 at 14:35
  • could you place a description of your chipset here ?! what machine you have there and what bios exactly ? - askubuntu.com/questions/31618/… - then list the details here ... - I assume that your hardware allow somehow mirroring datas for else purposes ?! - (hidden flash-disk ?) - – dschinn1001 Jan 25 '15 at 17:42
  • @dschinn1001: did you mean to add that comment here? This is a question about how files are arranged on the Ubuntu servers, not a request for help in finding an installer for any specific machine. – Paul Whittaker Sep 28 '15 at 16:44

The 1st page of releases.ubuntu.com seems to me to explain why:

Ubuntu Releases

The following releases of Ubuntu are available:

We are happy to provide hosting for the following projects via the cdimage server. While they are not commercially supported by Canonical, they receive full support from their communities.

The cdimage server also hosts releases of other Ubuntu images not found on this server, such as builds for less popular architectures and other non-standard and unsupported images. For Ubuntu Desktop and Server on popular architectures, please see the links above instead.

For old releases, see old-releases.ubuntu.com.

As canonical is a company that provides technical support, it should have should have such kind of separation.

Looking to the official links on www.ubuntu.com. They are all point to releases.ubuntu.com except Network installer and Ubuntu Kylin.

Another thing, they always try to minimize mirror size and mirroring daily builds just wasting of resources. Mirror script point only to releases.ubuntu.com

I couldn't find out any official note about such decision yet. But separation between releases and other builds back to 2005 at least. See Ubuntu Server Project Unleashed!. Even back to Oct 2004 with release of Ubuntu 4.10 which is the first release(just i386), Make a look on these few early mails from ubuntu-announce archive.

  • 1
    Hmm. That page was modified around June 2013, prior to which it simply said "other images". Do you have any posts or such indicating when or why this split was formalized? – muru Jan 22 '15 at 3:26
  • @muru, It seems not possible to get any thing in the archives (mail lists & wiki). as both hosts were used from the beginning with 1st release of Ubuntu, please see my last edit. – user.dz Jan 23 '15 at 22:25
  • Ok, thanks for the effort! I'll keep the bounty open a little while longer to see if anything pops up, if you don't mind. – muru Jan 23 '15 at 22:30
  • you are welcome, sure no problem at all – user.dz Jan 23 '15 at 22:32
  • Now it seems to be possible to find "official" installers (the same but running older versions...) – Wilf Aug 30 '18 at 17:33

As you pointed out, release.ubuntu.com is intended to hold more common installer image, whereas cdimage.ubuntu.com is for other images, like PowerPC or Kubuntu.

In my opinion, Canonical intended to split installers based on their popularity, since Ubuntu installer images are usually distributed using mirrors. Operators of mirror services can choose what type of mirror they want to copy.

For example, http://mirror.csclub.uwaterloo.ca/ubuntu-releases/ (Ubuntu mirror "University of Waterloo Computer Science Club") has images of releases.ubuntu.com and there is a link for cdimage server.

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