Summary

This comes up nearly every cycle, but is worth discussing: revisit whether it is feasible to maintain the 700MiB CD limit on Ubuntu images, or whether we need to shift to a larger image format. Consider:

This has been a controversial discussion, as expected. Please do not make edits to this page advocating one position or another or discussing details as in the Etherpad notes, as it will quickly become unreadable; instead, please use a talk page linked from this one.

Release Note

Ubuntu CD images may now be written directly to USB storage media using tools equivalent to dd. Programs such as Startup Disk Creator are now only needed if you wish to allocate additional persistent storage.

Image contents

Requirements for new features on Oneiric images include:

(Note that while GNOME Shell will be in Oneiric, it will not be on the standard images, so does not need to be considered here.)

Contrariwise, there are a number of items that could be removed from the images. Most of these are discussed further in desktop-o-cdspace, but also:

The following changes were suggested, but we will not be making them in this cycle:

Colin also suggested removing the LibreOffice Calc application from the default installation (4 MiB uncompressed). No decision was taken on this, so we will hold it in reserve.

Image format

The single-CD form factor has been controversial at one level or another since the foundation of the Ubuntu project, and there has long been pressure to move to a USB or DVD format instead. Discussing this from time to time is healthy. The typical arguments for changing are:

Typical arguments against changing are:

The Ubuntu DVD images currently consume most of the available space on a typical single-sided single-layer DVD (4.3 GiB), largely due to deliberately being a superset of the desktop, alternate, and server images. This is not an intrinsic property, and we could trim them down to something more in the area of 1 GiB if we were using these as our standard image format.

Shipping CD images is not exclusive of shipping USB images. We currently instruct people that they can use usb-creator with an Ubuntu CD image to produce a USB image. This is a certain amount of work and is not as good as shipping an image which works as a USB image directly. In Oneiric, we will finally ship hybrid CD/USB images which can be used as either, so USB users will not be disadvantaged. (usb-creator will still be useful for creating live USB images with persistent storage of modifications.)

Mark has indicated that he is a fan of "the laws of physics" - that is, the enforced limit of a CD image is better at keeping us within reasonable resource limits than an arbitrary limit for particular ranges of USB storage media.

Of course, in this case the laws of physics are the laws of engineering, and thus a little bit stretchier. Overburning has been common for a number of years, and we may be able to move to 720 MiB without significant side effects. (Five years ago this was demonstrably a problem for some people, but that may no longer be the case.) Alternatively, http://en.wikipedia.org/wiki/CD-ROM#Capacity indicates that a "700 MiB" CD is 360,000 sectors of 2048 bytes each (plus error correction), which is 703.125 MiB rather than the 700 MiB limit we currently enforce.

Decision: For Oneiric, we will remain with the CD form factor, but add hybrid USB booting. We will do our utmost to keep size down, and believe we still have many tricks up our sleeves that do not involve removing significant functionality. If necessary, we will break the 700 MiB limit and move to 703.125 MiB, or perhaps 720 MiB (in the latter case, probably trickling the extra space in over more than one release cycle).


CategorySpec

FoundationsTeam/Specs/OneiricCDSizing (last edited 2011-05-25 12:33:07 by cjwatson)