Live CDs Part III: Small Footprint Systems

[Editor's note: this is the third in a four-part series; the next installment will appear in the next week or two.]

In Part II of this series I looked at three examples of live CDs that provide desktop replacements. Each of those examples provided large numbers of tools, applications and features that a typical desktop user would find important. In essence, they all try to provide everything a desktop user would need.

On the opposite end of the spectrum you'll find small footprint systems. A small footprint live CD has the advantage of being able to run on memory limited hardware or even on much older processors, including pre-Pentium class machines. Each of the live CDs I looked at in this category came in under 120MB for the ISO, leaving lots of room for customization by end users.

Small footprint systems should boot into minimal configurations and allow extensive configuration so that they can be tuned for specific hardware very easily. The goal of a small footprint system should be to provide the base upon which more elaborate customizations can occur.

Olive

Olive is the successor of an older live CD called DeadCD. With an ISO image coming in at about 115MB, Olive is an example of a technology preview distribution because it uses newer software features not found in most other live CDs. Unlike the GNOME LiveCD (which we looked at last time), the technology here runs from the boot process through the desktop. This includes the use of GHLI, a Pascal script interpreter that was chosen over BASH for speed improvements for the init scripts. It also includes Enlightenment as the desktop environment instead of the more common KDE or GNOME environments but falls back to Xvesa for general graphics hardware support under the X Window System.

There is no login on Olive. The CD takes you directly to a root prompt. From here you can start up the Enlightenment desktop or use a lightweight desktop based on FluxBox. X configuration is done manually yet easily handled common settings of 1024x768, 24bit color at 60Hz. The desktop is clean and uncluttered, with extra pizazz provided by Enlightenment. Applications include MPlayer and Audacious media players, the Firefox browser, GAIM and XChat Internet messengers, and Abiword for office documents.

Olive correctly ran DHCP to setup the networking on the system without user interaction. It even set up the sit0 interface for IPV6-in-IPV4 routing, something my Fedora installations don't do by default (not that I know what to do with it yet).

Many live CDs use their own methods of extending the feature set of the CD. Olive uses a project called UniPKG to install RPMS, Debian and other package formats onto a running system. This adds features at runtime, however and isn't used to update the ISO image in any way. Documentation does not mention user accessible methods of extending the ISO image. Only the ISO is available for download (no source or build system).

Olive stays true to its purpose, coming in at only 117MB out of 229MB when running in the root shell without a GUI. Starting up Enlightenment takes this to 160MB while the light GUI (FluxBox) cuts it back to 150MB of memory.

Cleanliness:	8
Originality:	8
On Target:	7
Extensibility:	3

Puppy Linux

This live CD is more of a desktop replacement than a small footprint version, though even with OpenOffice installed it manages to keep the ISO under 90MB. Though small in size, Puppy Linux provides a wide set of applications and is thus more like a desktop replacement than a true small footprint environment. If you're new to Puppy Linux, the Wiki is a better place to start as the main web site is a bit more technical and slightly cluttered.

Puppy Linux supports a wider range of hardware than Olive at the expense of lots of initial configuration. The system supports multiple keyboard configurations. Unfortunately, the default keyboard is not a US QWERTY configuration so I have to change this each time I boot.

During boot up the system checks for a mountable USB device. If available, working files are saved to the device every 30 minutes. If it can't find a drive, it tells you that on boot up. Without USB, each boot requires you to go through extended configuration operations, like choosing a keyboard type. Though the USB support is a definite plus, the extra configuration required at boot time is annoying. Many systems make use of udev, lshwd or other mechanisms to do hardware configuration without user interaction.

Another area where too much user interaction is required is in configuring the X environment. Puppy Linux provides a choice of between probing for video hardware using an xorg tool or using a standard VESA fallback configuration. Whether probing succeeds or fails, the choice of falling back to the VESA configuration (which supports most video hardware) is still available.

The initial hardware probe for the X configuration defaulted to 1024x768 @ 16bit color. After probing, a menu is presented with other options. I was then able to change to 24bit color. Probing for audio hardware was painless but still required confirmation. Again, this all happens during the initial boot.

Puppy Linux uses ROX Desktop and Joe's Window Manager (JWM) for the desktop environment, keeping memory usage to a minimum. At boot up, using the VESA X driver, the system used 115MB out of 229MB.

The technology behind Puppy Linux includes SquashFS, for using compressed filesystem images, and UnionFS, for merging mount points from multiple SquashFS images. The system can be extended using the Puppy Custom CD Creator (PCCC) tool in conjunction with the PupGet package manager. Default applications include Abiword and Gnumeric for office documents, GAIM, Firefox and Sylpheed for Internet and mail access, and Snack and GXine media players.

Extensive documentation on how to extend or even build your own Puppy Linux distribution makes this a popular choice for the do it yourself crowd.

Cleanliness:	5
Originality:	7
On Target:	7
Extensibility:	7

Damn Small Linux

Damn Small Linux, more commonly referred to as DSL, which is not to be confused with the high speed Internet option from your local telco, is based on KNOPPIX technology. Like KNOPPIX, this very popular live CD has been a parent to many live CD children. Most are less well known than DSL though Feather Linux is also gaining popularity (and runtime size) on its own.

DSL had little trouble recognizing the EPIA M10000 board, probably because the core developers are fans of the EPIA line of mini-ITX boards. They even run a small mini-ITX store to help support their development of DSL. Boot up was clean and fast and went straight into an X session for the "dsl" user (as opposed to root) running the Xvesa display server. A minimalist browser called Dillo is opened at startup that points to documentation on how to use and configure DSL.

DSL uses the 2.4.26 kernel instead of more modern 2.6 kernels. This is an architectural choice. The 2.4 kernels are much smaller than the 2.6 kernels so using 2.4 helps keep a small memory footprint. The system correctly configured networking using a DHCP client at boot time.

Top reports 69MB used out of 223MB available but Torsmo (the desktop system monitor) reports only 29MB used out of 218MB. I'm not sure why there is a discrepancy. Either way, DSL still uses less memory than Puppy Linux or Olive.

The desktop defaults to using FluxBox though you can switch to Joe's Window Manager (JWM) on the fly. Applications include Firefox and Sylpheed for Web browsing and mail, Nano and VI for editors, xpdf for PDF viewing and xmms for multimedia. Office documents are handled by Ted and Siag.

An automated network-based installation is available that supports a wide range of applications. It's also possible to install additional applications using Apt and Synaptic, though use of Apt is not enabled by default (it's a menu option from the desktop). DSL can also install itself to a hard disk or USB drive simply by choosing the appropriate menu option.

DSL keeps to its word in providing a system that uses as little memory as possible while still providing a wide range of applications without having to install additional packages. Its dependency on older kernels may make it less suitable for more modern requirements.

Cleanliness:	7
Originality:	6
On Target:	8
Extensibility:	8

In the last installment in this series I'll look at a set of live CDs targeted at specialized situations. This is the class of live CD many people will want to explore, because the usefulness of a live CD is in it's ability to solve a particular problem or fill a particular need. The three CDs under consideration will be GamesKNOPPIX, a game player oriented live CD, the Ultimate Boot CD, a diagnostics and system recovery CD, and KnoppMyth, a MythTV based media system.

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