Bandwidth Place 2

I know this can be done but there's a twist in what I'm trying to do...

I was talking to one of the local computer repair shops that gets me to do some service calls for him. He wants to load up several different flavors of windows onto a hard drive and be able to install from that USB hard drive.

I don't think that can be done... for instance he wants to be able to install windows XP (all flavors), windows vista (all flavors) and windows 7 (all flavors) from this external drive. Sorta like you boot from it then pick what version of windows you want....


Then I got to thinking... why would you want to install from a USB port if you had access to a cd/dvd ?

The theoriticall limit of USB 2.0 is around 40 MB/s and the limit of IDE 133 is roughly 130 MB or so....

SATA 1.5 is 150MB/s and SATA 3.0 is 300MB/s

so even worst case scenario your making things take longer from the USB... even if your using a CD drive on an ATA 133 channel. Right?

USB 2.0 limit is:
Theoretical full-duplex 480Mbit/s divide by 2 for only-read or only-write = 240Mbit/s
240Mbit/s divide by 8bit = 30MByte/s
Of course none of the typical cheap flash drives can achieve that speed.

http://en.wikipedia.org/wiki/DVD#Technology
You can see on the table that the fastest speed listed for DVD-ROM read is still ~32MB/s. Optical drives are the last thing I'm going to expect to be able to take full advantage of IDE or SATA. Also SATA 3.0 is not 300MB/s, that would be SATA 2.0. SATA 3.0 would be 600MB/s.

My own testing:

Windows 7 Ultimate x64 installation, "Expanding" part, on Kentsfield-1 with

Patriot Dash 8GB:
5 minutes 22 seconds onto HDD
5 minutes 48 seconds onto Crucial C300 SSD (this SSD has a typical HDD-like write speed of 75MB/s)

DVD:
12 minutes, 33 seconds onto HDD

Access times are killer, CD/DVD being even worse than HDDs in this regard. It would also be the last variable for explaining why the flash drive installation was faster considering both USB 2.0 and DVD-ROMs read at about the same throughput of 30MB/s.

As for making an all-in-one installation device like that, it is possible but I'm pretty sure it doesn't exist yet and that there are no automated tools to fully create such a thing. You'd have to create your own boot menu to choose between them like all of those "ultimate boot cd" stuff do.