1. Computer Skills

How to Build a Custom RAID Setup for a Mac

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There’s a lot of good reasons to explore different ways of backing up information and preparing yourself for the worst, especially as more of our data ends up on our computers than ever before. I run a small business, and for me, having a large home storage and backup system for all my clients’ data is of critical importance.

In this tutorial, I’ll show you how to select the right storage and backup regime for your Mac.

Understanding RAID

RAID, which stands for Redundant Array of Inexpensive Disks, isn’t really a backup solution. In fact, RAID can be described perfectly by its name: it’s redundant. It’s difficult to explain what RAID is without understanding the different sorts of RAID, so I’ll simplify my explanation by saying that RAID allows you to configure multiple hard drives together as if they were one drive, letting your virtually stack them.

You need to know what you're building before you decide on what you buy. RAID allows two things: it allows speed, or efficiency (which is called striping), and it allows mirroring, which is redundancy. Three different types of RAID, that best summarize these factors, are: RAID 0, RAID 1, and RAID 10.

  • RAID 0: This is the most common setup in the market, where data is stored across two disks. Instead of using the disks independently, the computer only sees it as one and stripes the data across both. A bit of information about one file will be on one hard drive and the rest of it might be on the other. This allows your hard drives to be twice as fast, but it also means that they’re twice as likely to fail. If one hard drive dies in the RAID, that means that the other one is useless. Don’t think about RAID 0 as two drives; think about it as one ultra-fast and ultra-risky storage solution. You don't need any special enclosures for this; you can build it in your Mac's Disk Utility app by running the RAID function if you have two spare external drives lying around. The app's instructions are well-written and can quickly guide you through it.
  • RAID 1: This array mirrors both drives to each other. Again, the Mac only sees one drive, but it’s actually backing data up to both. This means that, should one of the drives die, you don’t lose all your data and can keep going until your replacement hard drive arrives. It’s not a backup solution because it doesn’t protect you from user error (accidentally deleting files) or natural disasters (say, a fire), but it does ensure your business has more guaranteed uptime. RAID 1 uses two hard drives and doesn’t come with the speed advantage of RAID 0. This is similar to RAID 0 in that all you need is a couple hard drives and the RAID function in Disk Utility.
  • RAID 10: This is a combination of RAID 1 and RAID 0. It requires four hard drives to use, and is essentially two RAID 0 sets mirroring each other. This means that you get all the speed advantages with less of the risk, but most people find this setup is prohibitively expensive. Not unlike RAID 1, this isn’t a backup solution, but merely redundant storage in case of a drive failure. You don't need an enclosure for this either, but because it requires four hard drives, RAID 10 will be a lot easier for you to maintain if you do have one. Your wire usage will be cut down if you use an additional enclosure, or purchase one from your favourite computer retailer.
RAID visualizedRAID visualizedRAID visualized
RAID visualized

This graphic, taken from my colleague Marius Massalar’s article about foolproof backups, visually explains the differences in RAID solutions.

Of course, there are many other RAID setups you could consider (or maybe even require, depending on your needs), The Wikipedia article on RAID drives is useful for further information regarding options.

For my purposes, I’ve decided to build a RAID 1 drive.

Qualifying Your Needs

You don't necessarily need a RAID drive, but many people would likely find them useful. Anybody working in client services should have as redundant a backup plan as possible—not just because they need to protect their work, but also because they might store invaluable financial information on their computers' hard drives. Replacing all of that is a costly endeavour.

Beyond that, RAID is much faster than a typical external. Those who regularly work with large files should also consider a RAID 0 drive. RAID drives, in conjunction with an offsite backup drive (which are important, particularly should there ever be a natural disaster in your office), are the most foolproof non-network-attached storage options available.

There are Internet-connected storage systems available (called NAS drives), but largely, I find they’re too expensive for most purposes, and read and write speeds aren’t fast enough for them to be truly viable for use in a working professional’s life—not yet, anyway.

There are a number of reasons you'll benefit from a RAID drive:

  • Small businesses could lose days of work (and consequently, days of pay) without proper backups, and should strongly consider the benefits of a RAID system.
  • Even if you work in a small office with its own backup system and consequently think a RAID isn't something you need, some exceptions do apply. Independent contractors with access to their clients' servers, for example, should still consider RAID. That will allow them to maintain a local cop of their client's drives should the server ever go down. (This has happened to me before; don't think it can't happen to you.)
  • Some people work in industries where redundant backups prove invaluable because of the amount of data you store (think music production, photography, design, and videography). In those cases, I'd argue RAIDs are essential. It is not uncommon for sound engineers, for example, to have clients come looking for old work years after recording. I tell clients I'll keep their important files for 36 months, and use it as a selling point for my business. In cases like that, a redundant backup is a lifesaver.

Option 1. Purchasing a Pre-configured RAID

When it comes time to purchase a RAID drive, there are a lot of choices to make. The variety of drives makes it easy to find a RAID suited for any professional's needs, but there are still some guidelines to keep in mind.

To begin with: you can buy a pre-outfitted RAID enclosure from just about anybody who makes hard drives. Pre-configured RAID enclosures include the hard drive shell and pre-configured matching hard drives. Seagate offers many different RAID drives. You might have heard about the popular G-RAID drive from G-Technology, or even any of the popular drives from LaCie, which Apple sells at their retail stores. Although they are easy to use, pre-configured RAID drives are clear compromises.

The G-RAID drive, for example, cannot easily be opened up. It comes in RAID 0 and it’s difficult to convert it to RAID 1. It’s also extremely expensive, which makes sense given their aluminum enclosures and build quality. But because you cannot easily replace the drives in the enclosure should something go awry, the G-RAID series is meant to be thrown away after a few years of use.

Many of the Seagate drives, which are made of plastic and come pre-configured as RAID 0, are similar. There's a how-to on Youtube that goes into the details of how to take apart and replace drives in a G-RAID unit; as you can see, it's a lengthy process.

The LaCie drives appear to be the exception to this rule, but buyer beware—LaCie asks you call their customer service to get a compatible drive issued out to you in the case of drive failure. Again, this feels like an unnecessary step in the process.

Option 2. Building Your Own

The other option, apart from buying a pre-made RAID drive, is to build your own by purchasing the enclosure and hard drives separately. This can be as easy or as difficult as you make it, and I’ve done hours of research to ensure upon the easiest solution possible.

Here are some things you’ll need to keep in mind when shopping for a RAID enclosure:

  • USB 2.0 is a very slow connection; if a RAID enclosure looks cheap, it likely uses USB 2.0 exclusively. USB 3.0, Firewire 800, or Thunderbolt are all faster than USB 2.0. RAIDs with support for faster connections come with a heftier price tag, but time is money. You'll save both in the long run if your backups are twice as fast.
  • Most enclosures have a short list of hard drives they won’t support, and they usually only support either 3.5“ drives or 2.5” drives—not both.
  • When shopping for drives for your new RAID enclosure, try to order as many of the same make and model as possible. This will ensure fewer compatibility issues down the road.

If you’re looking for an enclosure, OWC’s products come highly recommended. They sell everything from pre-configured RAID units to individual enclosures, and what you need is likely dependent on your computer's I/O.

If you own a Mac from mid 2011 or later that’s equipped with Thunderbolt, or if you have a computer equipped with USB 3.0, I’d suggest the Mercury Elite Pro Dual enclosure. It comes with USB 3.0 and Thunderbolt, has a relatively small footprint (it could easily fit on top of a shoebox or a hardcover book if you plan on hiding it beneath a desk), and the 2-bay enclosure comes in at $299.99. What makes it nice is that it works with just about any drive, it comes with two Thunderbolt ports (and the necessary Thunderbolt cable), and USB 3.0 is also backwards-compatible with USB 2.0. This bay is about as future-proof as you can get in 2014.

The I/O of your RAID enclosure can make a huge difference. Take a look at this review from Mac Performance Guide — the reviewer, using Thunderbolt, was able to achieve read and write speeds of nearly 300mb/s in RAID 0 configuration. Of course, speeds are half that in a RAID 1 mirror. Using USB 3, the reviewer clocked slightly higher speeds than that, which means that the more expensive bay really delivers better results.

If you have a Mac equipped with Thunderbolt 2, consider the Pegasus2 enclosure from Promise. $700 gets you a 4-bay enclosure that can operate in RAID 0, 1, 5, 6, or 10, and using Thunderbolt 2, you can achieve throughput speeds of 20gbps.

Thunderbolt 2 should double the sort of read and write speeds Mac Performance Guide got with the Mercury Elite Pro. Based on the Thunderbolt 2 specifications, you could likely transfer data faster than your hard drives would write it.

It's always best to future proof your tools to the best of your ability.

Setting Up RAID

After you purchase the RAID parts you need, you need to run Disk Utility. This part is easy. Thankfully, Disk Utility is one of the hidden gems of OS X.

If you bought a pre-configured drive, consider using the Erase and Partition functions just to make sure your hard drive is running to its best capabilities. Disk Utility can guide you through all these options. I'd recommend you format the disk as Mac OS Extended (Journaled) for best performance on OS X. This will guarantee it works well with your Mac. If you plan on using the hard drive with Windows machine, you'll need to use the MS-DOS (FAT) setting.

Formatting and partitioning your hard drive is the only step you need to take if you bought a pre-outfitted RAID driveFormatting and partitioning your hard drive is the only step you need to take if you bought a pre-outfitted RAID driveFormatting and partitioning your hard drive is the only step you need to take if you bought a pre-outfitted RAID drive
Formatting and partitioning your hard drive is the only step you need to take if you bought a pre-outfitted RAID drive.

If you bought the parts individually, you'll need to use the RAID tab. Give the set of hard drives a name and drag the drives you're assembling from the left toolbar into the RAID set list. This will combine your drives into a single set. From there, choose your RAID type from the list.

The Mirroed RAID Set is RAID 1 and the Striped RAID Set option is RAID 0. The Concatenated RAID Disk Set is another option entirely. That means the RAID is not arranged redundantly; instead, it's just a bunch of disks. You don't get the speed of RAID 0 or the redundancy of RAID 1.

Setting up the RAID is easy in Disk UtilitySetting up the RAID is easy in Disk UtilitySetting up the RAID is easy in Disk Utility
Setting up the RAID is easy in Disk Utility.

If you'd like to create a RAID 10 drive (or work in other combinations of RAID 1 and RAID 0 combined), you'll have to do this a couple times. It's more work than buying a pre-configured drive, but it's much more flexible later on.

Monitoring RAID

Another benefit of a custom-built RAID is that you have the ability to monitor your drives' statuses. Software like RaidEye, free, or RAID Monitor, $30, make monitoring your hard drives a much easier part of your existence. Both apps require the drive to be set up using Disk Utility (or the Command Line in Terminal, if you like coding your way to hard drive redundancy).

If you purchased a pre-configured RAID drive, you may not have any options here. LaCie offers a RAID Monitor app for Mac, but G-RAID does not offer a similar tool. These pre-configured enclosures also don't include any warning lights in the hardware, so it's even more difficult to tell if any of the drives aren't working properly. Building your own RAID drive proves doubly beneficial.

The Bottom Line

RAID performance isn’t cheap but, if you’re a professional, it’s beneficial to get the best storage unit you can. And although no hard drive is perfect, a redundant unit can help minimize onsite damage should a drive fail. The catch with this product category is that you really do get what you pay for: a cheap RAID drive without any high-speed I/O is going to be much less beneficial than an expensive unit with expansive and forward-thinking outputs.

Ultimately, you’re also the only person who owns your needs. Most people I know don’t need RAIDs, but I’d argue that those who run their own businesses—particularly if part of a small creative studio—have very little reason not to get one. These drives offer peace of mind for what I think ends up being a fair price in the long run, and they're fairly easy to set up. If you disagree, let me ask you: how much is your data worth?

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