One of the advantages of an open source environment like Linux is the myriad number of personalities involved in its development, future, and feature-inventory. When the available choices do not meet the needs of one person, he/she can create an alternative methodology, test it, and then offer it to the community for their use or not. Installation choices for Linux is no different: there are many different ways to install, create, run, and remove a Linux installation – far more than either Windows or OSX.
The installation media choices can be categorized into 2 major categories:
Category 1:: Physical media: CD, DVD, USB, or HDD
Category 2:: Network media: HTTP, FTP, NFS
In addition, the installation methods can be categorizes into 4 major categories:
Method 1:: Clean: installation that does not write to current OS storage media
Method 2:: Dual-boot: peaceful co-existence with current OS on same storage media
Method 3:: Replacement: overwriting of current OS with Linux on platform storage media
Method 4:: Upgrading: enhancing current OS to newer or different version of Linux OS
Reasons for Media Choices
For Todd, our fictitious Linux aspirant, to make the decision of which media installation is right for a particular situation, understanding the different choices is in order:
CD-R: This is the simplest form of Linux installation due to the large number of CD reader/writer devices in addition to an equal number of burning software programs that support the standard *.ISO format of the installation downloads. The process is very simple: download the *.iso file, burn it to a CD-R media disk using appropriate burning software, and then using the disk to boot the computer. The only major limitation of this choice is the 700MByte size limitation of the CD-R blank media disk.
DVD: The process of creating a DVD type media installation disk is exactly the same as for the CD-R except that the device must of course be a DVD, and the capacity of most DVD single layer/sided disks is approximately 4.4 GBytes.
USB: This choice is the newest physical media type that uses a USB memory stick of appropriate size (2-8 GBytes) to boot a Linux distribution. The main limitation is the necessity of the BIOS of the booting machine to support a USB boot option. The main advantages over the CD/DVD choice is the increase performance of a USB 2.0 port over a ROM reader, and the ability to both read and write data limiting the impact on the booting machine’s hard drive capacity.
HDD: Booting from a hard drive installation is very similar to the CD/DVD choice except that instead of booting from a separate device, the booting machine uses an *.iso format that is mounted as if it is a separate device. Due to problematic operation of the hard drive device drivers on some machines, this choice could be less reliable than the other more independent media choices. Also, there is higher chance of corrupting an existing OS implementation on the hard drive.
These choices usually require the setup of a network-reachable server that is then configured to use either the HTTP/FTP/NFS method of installation media choice. The installation directories are created with the installation content copied and verified to these directories. Setup and configure the appropriate server depending on the media choice (HTTP/FTP/NFS) to provide network access to the client platforms installing from these servers. For most network style installations, Todd will be required to create a special “boot CD” that will provide just the smallest amount of information for your client machines to find and select the appropriate media (HTTP/FTP/NFS) choice once the connection to the server is made. From here, the installation is similar to the CD/DVD/USB choice.
The differences between the network media choices are:
HTTP: This installation choice uses a web server to act as the storage device for the installation files and data. The most often used web server is the Apache web server software, and the main advantage of the HTTP choice is the much easier firewall configurations needed for HTTP connections over FTP or NFS. Disadvantages is the lower performance and lowered security.
FTP: If the FTP server requires a userid/password this information will have to communicated to the user or technician accomplishing the installation. A very reliable, large file transfer solution, the FTP choice should be used in an Intranet environment for better security.
NFS: This choice uses the *.iso format of files while the other 2 networking choices use the distribution normal file formats (RPM, DEB, etc.) Usually best when used inside a firewall (local) networking environment. This choice has the highest performance.
Resources from linux.com:
The linux.com site has several tutorials on the choices discussed in this article.
Difference between HTTP/FTP/NFS (discussion note)
Once Todd has decided upon the media type and which installation method he needs, he can begin to setup and configure his platforms to accept the Linux environment that meets his particular requirements.