What drive should I buy?
Everything you need to know to pick a backup drive
Long gone are the days when external hard drives were expensive and cumbersome beasts; you can now pick up 500GB or 1TB drives for well under £100 that will serve all your backup needs. If your requirements are more heavyweight, serious backup drives cost a little more but offer advanced features and very high capacities. Generally speaking, as long as a drive will mount on the desktop in OS X and is correctly formatted, it should be usable by Time Machine. This means that yes, even that old USB drive you have hanging about should do the trick – or even an internal drive you could stick in an enclosure or drive dock.
First things first
First, consider connectivity. The baseline for any external hard drive is USB 2, which is universally supported on any Mac new enough to run Time Machine. It’s not lightning-fast, but given that Time Machine tends to just do its thing in the background, this may not be a huge problem. If your average incremental backup is just a couple of gigabytes, a USB 2 drive will manage this just fine. Smaller models also usually power themselves over the connection too – one less power lead to worry about.
Newer Macs also support USB 3 and this is becoming commonplace in external hard drives, albeit usually at a slightly higher cost. It’s faster, so great if you need to back up quickly. Thunderbolt is Apple’s latest connector type and is incredibly quick; it’s ideal for backing up large amounts of data quickly or for using in a daisy chain of other Thunderbolt devices to cut down on cabling. These drives are costly, so are probably better suited to pro users. Mostly, your backup drive will be a traditional, spinning hard drive because these are cheaper and more capacious than solid state drives. In truth, an SSD is extremely quick, but they’re overkill for a simple backup solution.
In terms of size, it’s advisable to use a backup drive that’s at least twice or even three times the size of your Mac’s internal hard drive, because it will take longer to fill up and offer a longer version history for your files. Some models like the MacBook Air have relatively small internal drives and iMacs have larger ones, but your needs will be determined by how you use your Mac. If, for example, you have a MacBook Air with a 128GB internal drive and use it mainly for Office tasks and storing a few pictures, you’re going to get plenty of backup life out of a 500GB external drive. If, on the other hand, you have an iMac with a 3TB internal Fusion Drive and you actively work on lots of high-res pictures, edit movies or do anything else that regularly generates large numbers of large files, the size of your backups is going to be much greater.
RAID(ers) of the lost art
Remember that Time Machine creates backups of new and modified files, so if you render a project out of iMovie, back it up and then later add more footage and render a new version, all that new stuff is going to get backed up in addition to the previous version. While this provides great recoverability for your files, it can use up a lot of space. For heavy users, a more weighty solution is required.
Mirrored RA ID drives are single units housing two or more physical drives but that appear to the Finder as a single volume. They can be configured in different way; configured as RA ID 1, a RA ID drive copies the same data to more than one disk during backup so if one disk fails, you can replace it and the RA ID array will rebuild itself. Configured as RA ID 0, data is written to both drives simultaneously, which speeds up the copying process. The downside of this is that if either drive fails, your data is gone. In general, you shouldn’t use RA ID 0 for backup.
Network Attached Storage (NAS) drives are also useful because they connect to your wireless router or LA N using Ethernet so you can back up wirelessly – and they sometimes come with more than one drive inside, which can increase data security. Being self-contained units with a processor onboard, they run their own operating system and can be configured through a browser. Some of them have Time Machine support built in, which means they can be specified as networked backup drives in Time Machine’s preferences.
Plus, because they’re capacious and run on a network, NAS drives are ideal for backing up multiple Macs wirelessly or over LA N. Apple actually provides an alternative to using a NAS: the Time Capsule, which isn’t just for doing backups.