[TheJeffsta]

Is it possible to install servers (apache, ftp, etc.) on a USB attached external hard drive that doesnt have an OS and then be able to connect it to another computer and all of them still working?

Just a question that has arrisen after I was unable to install Vista over USB :( - stupid Microsoft!!!!!!

[chewett]

technically if you use the computor it is connected to as the server but use none of its data and then put all the data for your website on the external hard disk you should be able to use it theoretically

but the conflicts of not having the server in 24 7 and the usb would have to supply a lot of power over the wire i am not sure if it would work for a while

[Micro]

It's possible, but only if the machine is running linux/windows (Dont expect to plug it into a windows machine if the server is running linux binaries), but you would need to start the processes for it manually.

[alpha1]

there is this lite version of XAMPP (Apache Mysql PHP Perl) for windows
which can be run from a pendrive/usb drive

also try http://www.portableapps.com they are working on the same thing with XAMPP.
Edit:
i use XAMPP on my desktop its about 150+MB

but the XAMPP Lite version is much less.

goto http://portableapps.com/apps/development/xampp it has all the details if you want
Edit:
heres another one i found The Uniform Server (http://www.uniformserver.com/) The Uniform Server is a WAMP package that allows you to run a server on any MS Windows OS based computer. It is small and mobile to download or move around and can also be used or setup as a production/live server.

[halohalo]

http://www.madtux.org

Sells both Ubuntu and Knoppix Linux on USB pendrives. Both versions of these Linux OS installs boot up and run completely from a usb drive. I have the Knoppix version and have not noticed any performance problems. You may want to consider one of these options.

Another route is downloading DSL (Damn Small Linux) which has an option for you to install their lightweight version of Linux on a USB Pendrive by yourself. Included with the install of DSL is a lightweight webserver. I've tried this and the only difference between the Ubuntu and Knoppix versions is that the footprint is much smaller: 50 MB total for the entire DSL installation.

You can also consider running a LIVE distribution of your choice of Linux OS flavor. LIVE distributions are versions of the Linux OS that are runnable solely from CD-ROM and RAM memory. Once you've loaded up the OS, a RAM memory resident install is VERY fast. (Save for infrequent reads from the CD-ROM) LIVE distributions are cheaper (actually, free) compared to using a pendrive version which usually costs $40+ USD.