Your data is the most important aspect of your computer, and unfortunately we often don’t realize this until we’re faced with the possibility of having lost exceptionally valuable (if not priceless) work. This can happen as easily as a computer suddenly shutting off on you and no longer booting, or when you attach an external hard drive containing all of your files, only to find it will not mount and cannot be repaired.
At these moments of realization, you’re confronted with limited options. Therefore, the best approach is to ensure you never get to this point, at least from the standpoint of your data, and the easiest way to do this is to always keep a copy of your data on more than one physical device. Whether you employ Time Machine, manually copy files, use a system cloning tool, or another routine, provided the data is duplicated to at least one secondary volume then you greatly reduce the chances of it falling victim to a hardware failure. The formula is easy:
- Get an external drive with the capacity for all of your data (At least the same total capacity of the drive currently storing your target data).
- Set up a backup routine (Time Machine, a clone, etc.) using the drive
- Repeat steps 1 and 2, preferably keeping the drives in different physical locations
- Consider using OS X’s drive encryption routines to protect your data from theft
Most modern USB hard drives, and especially those from reputable manufacturers (Western Digital, Seagate, Toshiba, LaCie, etc.) will be fully compatible with your Mac’s hardware and OS X. There are very few modern drives that are built for one platform but which will not work on another. Nevertheless, for any device you are considering buying, be sure to check for such compatibility limitations, and if you find one, then consider avoiding it. Even if the device is built only for OS X, this means you may have trouble accessing files from it if you only have a Windows-based system at your disposal. Furthermore, a drive that is built just for a Mac will offer no advantages over a similar drive built for all platforms.
Once you know the capacity of drive that you need for your data, there are generally two aspects to consider for an external hard drive, its physical size, and its speed. Overall, small portable drives are convenient, but break easier. Expensive drives may be faster by using SSD with the latest USB or Thunderbolt technologies, but often these are simply not needed unless you plan on doing extensive and regular data transfers to the device.
For the most part, other bottlenecks in your data workflow will prevent you from fully using a fancy external hard drive’s capabilities. Technically you can get an external SSD (even a striped RAID of two or more SSDs), and connect it to your Mac via Thunderbolt to give you a drive as fast as your Mac’s internal drive, but this is overkill unless you plan on using the drive as an active workspace. For basic and longer-term storage, a conventional hard drive will suffice and give you greater storage with acceptable speeds, for far less.
Dos and Donts
Regardless of your choice of drive, there are several dos and donts for setting it up, that will help ensure the drive and your data stays free from problems as you use it.
Don’t: Upgrade internal hardware
You may be tempted to try replacing your Mac’s internal drive with a faster or larger drive. Unless your Mac’s drive is failing or the Mac specifically supports drive upgrades, then it is best to leave the system as-is and rely on external storage for adding capability. This is especially true for systems that are still under warranty.
Do: Freshly format your drive to an OS X-native format
Most drives come formatted to either NTFS for internal drives, or the universally supported FAT format for external drives. While these can both be read by a Mac, with FAT being both readable and writeable, they are not the most compatible with OS X. Your best bet for data stability and security is to format the drive to the Mac OS native “Journaled HFS+”, which appears as “Mac OS Extended (Journaled)” in Disk Utility. Journaled filesystems offer transactional writes, which ensure data changes are fully written before committing them. If not, such as in the case of a hang or power outage, then the partially written data will be discarded.
Don’t: Install manufacture-specific drivers for standard drives
If your drive device is a standard single-drive setup (ie, it is not a RAID array), then you should not at all need special drivers for using it. By installing drivers that are not part of the OS, you chance an update to either the Mac OS or the driver may break something. In most cases the drive you have will work just fine (and perhaps better) without the manufacturer’s drivers or management software. The one exception to this is for RAID drives, which may require tools from the manufacturer to manage.
Do: Store all of your data in at least two different locations
Regardless of the other dos and donts suggested here, the most important thing you can do for your data is to keep updated copies of it on completely separate devices. You can do this by way of a Time Machine backup or clone, but if your backup drive is simply a partition of your main boot drive (ie, you split your drive in half using Disk Utility), then you chance a hardware failure knocking out the backup along with the original data. Therefore,
Drive recovery tips in the event of failure
Provided you have your data replicated and encrypted, a hardware failure or loss of a drive will not be an issue, as you can always purchase a replacement drive. This is the proactive key to data security. However, if your drive is showing troubles (specifically errors and warnings), then try once using Disk Utility to check for and repair errors. If you cannot make the drive at least readable with these routines, then unplug the drive and consider how much you need the data on the drive. If the data is ultimately not important but you would like to try recovering it for convenience, then you can try using third-party tools and additional resources to recover the data. If the data is essential and irreplaceable, then your best bet is to leave the drive alone until you can contact a proper and reputable data recovery service.
The one caveat here is encryption. If your drive is encrypted and you cannot unlock it either from a hardware failure or loss of a password or other recovery keys, then the drive is effectively wiped. You can set it aside in hopes you can remember the password, but if not then you might be best off by just formatting the drive and setting it up again. After all, it is just effectively an empty drive you have at your disposal.