Chapter 6. Using the Ubuntu Installer If you are installing at a lower priority (e.g. in expert mode), you will be able to make more decisions yourself. You can choose whether or not to use the security and/or stable-updates services, and you can choose to add packages from the “contrib” and “non-free” sections of the archive. If you are installing from a CD or a DVD that is part of a larger set, the installer will ask if you want to scan additional CDs or DVDs. If you have additional CDs or DVDs available, you probably want to do this so the installer can use the packages included on them. If you do not have any additional CDs or DVDs, that is no problem: using them is not required. If you also do not use a network mirror (as explained in the next section), it can mean that not all packages belonging to the tasks you select in the next step of the installation can be installed. Note: Packages are included on CDs (and DVDs) in the order of their popularity. This means that for most uses only the first CDs in a set are needed and that only very few people actually use any of the packages included on the last CDs in a set. It also means that buying or downloading and burning a full CD set is just a waste of money as you’ll never use most of them. In most cases you are better off getting only the first 3 to 8 CDs and installing any additional packages you may need from the Internet by using a mirror. The same goes for DVD sets: the first DVD, or maybe the first two DVDs will cover most needs. If you do scan multiple CDs or DVDs, the installer will prompt you to exchange them when it needs packages from another CD/DVD than the one currently in the drive. Note that only CDs or DVDs that belong to the same set should be scanned. The order in which they are scanned does not really matter, but scanning them in ascending order will reduce the chance of mistakes. One question that will be asked during most installs is whether or not to use a network mirror as a source for packages. In most cases the default answer should be fine, but there are some exceptions. If you are not installing from a full CD or DVD or using a full CD/DVD image, you really should use a network mirror as otherwise you will end up with only a very minimal system. However, if you have a limited Internet connection it is best not to select the desktop task in the next step of the installation. If you are installing from a single full CD or using a full CD image, using a network mirror is not required, but is still strongly recommended because a single CD or image contains only a fairly limited number of packages. If you have a limited Internet connection it may still be best to not select a network mirror here, but to finish the installation using only what’s available on the CD and selectively install additional packages after the installation (i.e. after you have rebooted into the new system). If you are installing from a DVD or using a DVD image, any packages needed during the installation should be present on the first DVD. The same is true if you have scanned multiple CDs as explained in the previous section. Use of a network mirror is optional. One advantage of adding a network mirror is that updates that have occurred since the CD/DVD set was created and have been included in a point release, will become available for installation, thus extending the life of your CD/DVD set without compromising the security or stability of the installed system. 63 6.3.5.1.2. Using a network mirror 6.3.5.1.1. Installing from more than one CD or DVD