Setting up Time Machine the first time

I want to activate Time Machine, but I am getting stuck during the very first steps.

I have an EHDD connected to my AE. I am able to connect to the EHDD wirelessly. I wish to use my EHDD as the storage device for Time Machine.

My EHDD is not listed among the backup disks (there are none) and I can continue by setting up Time Capsule. This allows me to change the settings of my AE, but I can't see what I should change to enable Time Machine.

One last question, does Time Machine compress the data? I have about 40 GB on the EHDD but have used 100 GB on my Macbook Pro. Is it out of the question that I use my EHDD as my backup?

Take a look here:

Stephan Fassmann: How to Setup Time Machine on an Airport Extreme Basestation

Trolle said:

One last question, does Time Machine compress the data? I have about 40 GB on the EHDD but have used 100 GB on my Macbook Pro. Is it out of the question that I use my EHDD as my backup?

Click to expand...

Your backup drive for Time Machine should be (and is recommended to be) larger than your computer's hard drive. You could get a 250 GB EHDD with no problems. You can look at Best Buy, they sell many varieties of EHDDs, many under $100.

EHDDs at Best Buy

*note: the site shows sale prices, the regular prices are in small font in blue underneath. The page I linked shows a Western Digital 1TB EHDD for about $87, but it's regular price is about $350. Also look at the ratings for the products. Just giving you a heads up

For some other information, you won't have to worry about filling up the EHDD either, Time Machine will delete the oldest backups to make room for newer ones.