Bootinf from external USB and CompactFlash devices

Q Regarding booting from an external USB or CompactFlash device - I have four questions: 1. Is it possible to boot from a USB flash drive if your BIOS doesn't support USB booting? 2. Can a boot CD with Smart Boot Manager pass off the process to the USB? 3. Is it possible to fit an uncompressed Knoppix or Kanotix CD to a 2MB CompactFlash or USB? 4. What parts of the system would be better off on the hard drive, eg swap or logs?

A I'll answer each of your questions in turn. 1. Yes, but you will need a boot floppy to do this. For example, Puppy Linux has a floppy disc image on the website that can be used to boot it from a USB flash disc. See www.puppylinux.org. 2. No. Smart Boot Manager does not support booting from USB devices. 3. It should be, although you shouldn't uncompress the image. USB reading is quite slow, so any reasonably powerful machine would probably uncompress faster than it reads, making the compressed image faster. There are instructions for installing Knoppix on to a 1GB (or larger) flash disc at www.knoppix.net/forum/viewtopic.php?p=64999#64999. Alternatively, Damn Small Linux can be installed on a USB device, and DSL is a cut-down Knoppix. So you should be able to put a full Knoppix on to a 1GB flash disc by booting DSL, running sudo dsl-usbinstall to install it to the USB device and then replacing the knoppix/knoppix file with the full-sized one from a Knoppix CD. 4.

Anything that involves writing, especially frequent writing like swap and log files, should not be placed on the flash device. Flash memory has a limited write lifetime, typically between 100,000 and 1,000,000 writes (and as little as 10,000 writes for older devices). If the system is continually writing to the same area of memory, it could fail in a few months. Your choices are: to put these on the hard drive, which limits portability; to write logs to a RAMdisk and copy it back to the flash drive on shutdown, which would limit the writes to one per session; or to use the JFFS2 filesystem from http://sources.redhat.com/jffs2. This is a special filesystem designed to address this problem with flash devices. If you want a ready-made distribution for a flash drive, try Flash Linux from http://flashlinux.org.uk.

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