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Startup
An instance is a running LIVE Services system on a server somewhere.
There is a CD designed to boot all possible systems. This contains a custom-built Debian boot image. Customisation includes a minimal package selection, options for the opening splash screen, some locale settings, and the hook into LIVE Services. Most (but not all) PCs can boot from such a CD.
The aim is to keep the medium as simple and stable as possible. The hook brings in some common (all systems) functionality from online, including the registry of servers. If the server is recognised it will complete the customisation necessary (for an LS1 or LS2 system).
There is also a USB stick designed to boot all possible systems. The only difference between this and the CD is that a second partition on the stick contains caches of Debian packages necessary for installation. Having these caches available cuts startup time and guarantees a consistent result. Very few PCs cannot boot from a USB stick.
The remaining startup is specific to the system (LS1 or LS2) and the particular server it is being run on. For example LIVE Services will automatically know whether to run a 'head office' or 'satellite' LS1 system.
Keeping all the volatile stuff online makes fixing problems much easier, and all fixes are completely persistent. Rebooting is seldom necessary because systems can automatically bring in changes posted online, and re-configure as and when necessary. The actual amount posted is small (about a megabyte) being zipped-up scripts and configuration files mostly.
Mapping and other fixed data, which used to be stored on the medium too, is now stored on the Synology fileserver. This is another great improvement in the management of the medium and use of system memory. It also opens the way for much more serious applications.
2017-09 update: the management of package caches on USB sticks is fully automated; although reliable, CDs are very slow to boot and will only be needed in exceptional circumstances. These improvements further simplify software update and distribution.
2020-02 update: new media are now delivered ready-to-go via SSH tunneling; package caches can be recreated if necessary.
2021-08 update: support for UEFI booting is added.
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