[mdlug] Suggestions for flash-drive Linux?

[David Favro]

Sorry for replying to an older post, I'm catching up on some reading...

Robert Meier wrote:
> Unless your bios can boot from usb, you will need boot from a CD/DVD.
>   
That's true and I don't know about new machines but many not-very-old
machines can't boot from USB, so if you want your USB-drive Linux to be
reasonably portable, you'll need to be able to boot it from a live CD. 
This is relatively easy with Knoppix.  But...
> If you are already using a CD/DVD, I see no benefit from putting the OS
> anywhere else.
> The flash drive is then the storage for your home directory,
> OS extensions (e.g. /opt), ...
>   
This is a reasonable idea especially if you're using a relatively small
drive and don't want to use up space on the USB-drive for the O/S, save
it for your files.

BUT, there *is* a benefit from getting the OS off the CD, a *big* one:
speed.  I don't know about flash, but I can tell you that a USB-2
hard-drive is a lot faster than reading from CD.

The biggest problem is that the CD drive spins down after a period of
inactivity (let's say while you're typing a document) and when you then
need access to O/S resources (run a command that isn't in cache or just
access a portion of the text segment of a running program that isn't
currently in RAM), the CD drive must spin up which makes for a *very*
noticeable delay.  Even a USB-1.1 device will seem very snappy by
comparison.

And even once it is spun up, my experience has been (but someone with
real numbers could clarify) that CD drives don't produce the same read
rate as a 2.5" IDE in a USB-2.0 box, even if the CD drive is rated "X
times read" where X is a relatively large number (though I sometimes
work on older machines where the CD drive may not be as fast as what
they're making these days).  Regardless of the CD drive speed, I can
tell you from experience that reading the O/S from the USB seems
snappier than from the CD, even if it is already spun up.

Finally, some live CDs such as Knoppix store the entire disk image in a
compressed format which is expanded as it is read.  I doubt that this
adds much overhead even on a very slow CPU, but it might add a little. 
Of course, with a slow enough CD read rate, it will result in faster
read performance, since less data must be read! :-)

But the real killer is the spin-up.  Live CDs are OK for some
situations, but if you really want to use one for all-day-long serious
work, and you can possible install to USB, I advise doing it.  Then keep
the live-CD as a "bootloader" for machines that can't boot from USB.  I
do a custom remaster of Knoppix that (among other things) automatically
boots from USB without my having to type any "cheat codes" (boot
parameters).

Like some others in this thread, I think a small magnetic drive in a USB
box is much better for this purpose than a flash "thumb" drive, and only
slightly more expensive and bulkier.

Just my opinion,
-- David Favro