Thank you very much...it all makes perfect sense. I have a a new model Alu iMac about 3 months old. The capacity says 232.57GB with 208.28 available. Thank you for your help and look forward to your next instructions. I understand the value of only partitioning into 2. I think having 2 externals is not an option at the moment. I have also seen a Seagate Freeagent Desk for Mac and am thinking of purchasing this one instead of the WD. Any thoughts on that appreciated.
No problem on the two drives- just wanted you to be aware of the risks so you could make a decision based on what works for you.
Originally I was going to recommend a larger external drive, but now seeing how little of your internal drive has been used, I have rethought that somewhat. Not knowing what kind of price differentials there are between a 500Gb drive and a 750Gb or 1 Tb drive (not a huge differential in the US) it makes it hard to make a recommendation, but I will say that you should initially get the biggest one you can comfortably live with cost-wise. Getting a single drive with a large capacity is always going to be cheaper than getting a smaller drive now and having to add a second drive later since it would add the cost of another case, power supply, etc.
Now since you have the late model iMac, you have a FireWire 800 port available to you, so choice of your drive is important if you want the maximum performance with it- and picking a drive able to connect to the FireWire 800 port will stand head shoulders above one that only connects via USB but the USB only is cheaper than a drive with FW800. Even one with FW400 would be higher performance than a USB only drive, but that is a choice you need to make. Again, I would say to get one with the best performance level you are comfortable purchasing, using the scale of USB being lowest performance, FireWire 400 being in the middle and FireWire 800 being the best.
The WD MyBook Essential that you mentioned is indeed USB only, but they make many other models in the MyBook line which can be seen at the comparison page for them at
Western Digital MyBooks Drives page. The MyBook Home Edition is the lowest one with FW400 and the MyBook Studio Edition is the lowest one with FW800 BTW.
In the Seagate Freeagent line it is similar- various models with different interface capabilities. The Freeagent Desk you mentioned (and the older model Freeagent Desktop) is USB only, while the Freeagent XTreme (and some models of the its previous generation brother the Freeagent Pro) have FireWire 400 in addition. I bring up the older generation drives in that line because they have only recently been changed and other than the case design I have not heard much of any performance changes- and the older ones are available on Amazon and such for reduced prices.
So anyway- get the largest fastest drive you are comfortable getting and you won't regret it!
Let's skip ahead. Your drive has arrived and you are ready to prepare it for use with TM and your files by making it two partitions, so you connect and power up your drive. it may or may not appear as an icon on your desktop at this point but we will fix that next. Start up Disk Utility found in your Utilities folder. Now:
1. Find your new drive in the left hand column and select it by clicking the name once.
2. Click the "Partition" tab at the top right of the page
3. At the top left, use the pull down menu under "Volume scheme:" to change it from "Current" to "2 partitions".
4. You can keep it at two equal partitions as it is presented to you, or you can drag the line between the two partitions to change their relative sizes. (For practicality your TM partition should be at least 250Gb, but preferably larger since we want it to back up your second partition too which is why I recommended buying the largest drive you could).
5. Click the upper partition in the map, and give it a name under "Volume Information" (make it easy to remember to avoid confusion later- perhaps just "Time Machine" for the TM backup and another name for the second partition.) Select "Mac OS Extended (Journaled)" for the "Format" field.
6. Click the bottom partition in the map and do the same thing.
7. IMPORTANT: Click the "Options" button at the bottom of the window and insure that "GUID Partition Table" is selected from the list.
8. Click "Apply" and you will get a summary screen before it goes to work. If everything looks OK, click "Partition" and sit back while it does its thing. Don't get too comfortable though, as it will only take 15-30 seconds!
Ok, you should now be able to quit Disk Utility and two new drive icons should be on your desktop with the names you gave them in DU. Shortly after you quit DU, you will be asked if you want to use the first partition with Time Machine so you can go ahead and click yes if it is asking about the correct partition. If it is not, then click no and it will then ask about using the other partition.
BTW- Once you have Time Machine going, be sure to go into the Time Machine preferences pane in System Preferences and click the "Options..." button. In there you will see a list that is titled "Do not back up:"- if your second partition appears in that list as I suspect it will, click it and then click the "-" sign at the bottom to remove it from the list so that TM will back it up in addition to your internal drive.
So there you go. Your system will then go ahead and start copying files for the initial Time Machine backup which will not take too terribly long since you really don't have much on your internal drive yet.
Good luck with it all- and don't hesitate to PM me if I missed anything!
