Wow...
If you ask me, they really need to properly train their salespeople.
What you were told to do could not have been more wrong.
From a photographer's standpoint, first let me make a suggestion to you.
I would suggest you go and pick up this book.
www.thedambook.com
Written by a photographer, it is an EXCELLENT read covering all aspects of digital asset managment, related specifically to photographers. Not only does it cover cataloging software, metadata, etc (the logistical side of things), but it also covers the physical (hardware) side of proper asset managment.
Seriously, check it out. It will really help future proof your image archive.
But anyway....
First: RAID.
For backing up your images, RAID is a very poor choice. The only thing it prevents against is physical drive failure. It provides no protection against things such as fire, theft, data corruption, etc. If you corrupt a file, it INSTANTLY mirrors it to the other drive. Then, both files are corrupted.
You are much better off using two separate drives, and manually backing up the data from one drive to the other. (By manually, I don't necessarily mean dragging and dropping files. You can always schedule backups with programs like SyncronizeXPro, or Chronosync). RAID is great in ADDITION to this manual, controllable backup method, when it's used for files you are currently working on, but it only protects from drive failure. Even a RAID needs to be backed up to your image archive.
Now this brings me to my second point: Partitioning / Multiple drives.
There are a few issues with partitioning a single drive in your situation. First of all, backing up from one partition to another is not creating a BACKUP at all. You're just duplicating files on the SAME PHYSICAL DRIVE. What happens if this drive fails? You lose everything. Instead, you want to have two SEPERATE hard drives. This way, if something happens to one, you have a second physical unit. In addition, partitioning also has another downside, performance loss.
Scratch Drive:
Every hard drive only has one path data can flow through. One bottleneck. If you use a partitioned drive, especially with one partition for scratch, you will be limiting your performance by filling up that bottleneck with two simultaneous requests for data. (Of course, this is not an issue if only one partition is accessed at a time, but this would not be the case if you are working on an image off of one partition, and using another for scratch.) This becomes even more of an issue when used for scratch, as scratch disks need SPEED. Photoshop uses your scratch disk as additional RAM (just in a different form). The faster it can move data to and from this drive, the much better off you are. Again, you are going to want to have a seperate drive. Ideally, two drives in Raid 0 (Striped data). Since the data on your scratch disks is not being permanently stored there, there are no real data security issues in this situation. In fact, since Raid 0 will speed things up to almost twice as fast, it's a very desirable thing to do.
So anyway...what do I suggest you do?
Well, of course it depends on your budget.
Scratch: Ideally, I would advise you to get two internal drives, and use software Raid 0 for your scratch disk. However, if you can't do that, at the very least get yourself an internal (or eSATA) Raptor drive. If the Raptors are too expensive, go with a 7200.11 Seagate Barracuda (although this choice is debatable, but from what I have read, it is the fastest 7200RPM drive out there). Either way, do what you can to use the SATA interface. The speed advantages over FW800 are very important for scratch usage. To sum it up, the FASTER the better.
Backup: If you don't mind spending a little extra money for SATA connection, I would go that route. It will give you better performance, but, I suppose it isn't really necessary for just backing up your images (as long as you're more patient than I am). Just make sure you stick with two seperate drives, and check out the software I mentioned above. Now, if I were in your shoes (which I was a few years back), I would make my backup plan an easily expandable and future proof one. (Really, check out that book) I would build myself a multiple hard drive enclosure, that can use swappable drive trays. That way, you can easily add new drives to expand down the road. Check out
www.macgurus.com. I'm currently running one of their 2-Bay burly SATA enclosures (but you can build one for FW800 as well). I would keep one drive plugged in and mounted, with the other one unplugged. Then whenever time comes to backup, just slide in the other drive.
EDIT: Just read the other posts that were added while I was typing this. Since you have a MBP, I would DEF go the eSATA route. The eSATA ExpressCards are relatively cheap (about $50). I'd get yourself a 3 bay port multiplier enclosure (the port multiplier just means you can use more than one drive over one cable, since the card only has two cable slots). I don't know what camera you are shooting with, but trust me, if you ever get into the higher MP cameras, and get into multilayer files in Photoshop, you are really going to appreciate the eSata connection. Again, check out
www.macgurus.com
