Choosing one or more hard drive can be as simple as making do with what you already have installed in the Mac; you can also add one or more internal or external drives. If you’re going to buy additional hard drives, look for ones rated for continuous (24/7) use. These drives are sometimes referred to as ‘enterprise’ or ‘server’ class drives. Standard desktop hard drives will work as well, but their expected lifetime will be reduced since they are being used in continuous duty and they weren’t designed for it.
- Internal hard drives. If you’re going to be using a desktop Mac, you have some options for the hard drive(s), including speed, connection type, and size. You will also have a choice to make regarding hard drive cost. PowerMac G5 and later desktops use hard drives with SATA connections. Earlier Macs used PATA-based hard drives. If you plan on replacing the hard drives in the Mac, you may find that SATA drives are offered in larger sizes and sometimes at lower costs than PATA drives. You can add SATA controllers to desktop Macs that have expansion buses.
- External hard drives. Externals are a good choice as well, for both desktop and laptop Macs. For laptops, you can gain a performance boost by adding a 7200RPM external drive. External drives are also easy to add to a desktop Mac, and have the added benefit of removing a heat source from the interior of the Mac. Heat is one of the prime enemies of servers that run 24/7.
- External connections. If you decide to use external hard drives, consider how you will make the connection. From slowest to fastest, here are the connection types you can use:
You can find a breakdown of the interface speeds in the About: Macs review of the OWC Mercury Elite-Al Pro external hard drive enclosure.