Backup of Your Backup – Part 3: RAIDS

Continuing on the the theme of redundant backups, nothing is more fitting than discussing RAIDS: Redundant Array of Independent Disks. RAIDs are commonly used by businesses and pro-users but they can also provide solutions for home users as well depending on one’s needs. While there are several types of RAID options, today we will be discussing mirrored software RAIDs and hardware RAIDs. This does move towards the more advanced application of backups so I don’t recommend RAIDs for basic computer users.

The simplest RAID backup solution is RAID 1, or a “mirrored RAID.” This type of RAID allows you to use at least two hard drives of equal size and it simultaneously backs up information to the drives. You can do this with at least two same-sized external drives or two same-sized internal drives if you have a computer that supports multiple internal drives. The obvious benefit here is that if one of the drives fails, you have a second identical drive to fall back on. While this is a great solution for a backup volume (Time Machine, clone, etc.) it can also be a great primary boot volume solution if you have a machine that supports multiple internal hard drives.

The only real drawback of a mirrored RAID is that the drives will perform slightly slower than usual since data is being written to two drives at once. While this won’t affect most users, if you’re a graphic designer or if you’re creating video or music, drive speed is an integral part of your workflow. While a mirrored RAID would still be a good backup option, I wouldn’t recommend it for your primary volume or scratch disk.

The easiest way to set up a mirrored RAID is by using Disk Utility (/Applications/Utilities). When you have both external or internal drives mounted and formatted as ‘Mac OS Extended (Journaled),’ click on the RAID tab. Drag both volumes that you’d like to RAID into the RAID window. Name the RAID and set the ‘RAID Type’ as ‘Mirrored RAID Set.’ I also recommend pressing the ‘Options…’ button at the lower left of the window and checking the box to ‘automatically rebuild RAID.’ Now press the Create button on the lower right; the drives will be reformatted and you’ll be good to go. If you’d like to use the mirrored RAID as your Time Machine backup destinatio n you can now go to System Preferences > Time Machine and select the RAID as your backup destination.

One thing to keep in mind is that Disk Utility will always need to erase the drives that you’d like to RAID when it creates the new RAID set. There are a few third party RAID software utilities that are able to create RAID sets without erasing the volumes (though I suggest backing up the data just to be safe). The most popular of these is SoftRAID, who just released an updated version of their fully-featured software RAID utility in May. Along with being able to create RAIDs on the fly, SoftRAID features accelerated mirror rebuilds, email notifications of degraded RAIDs, an optional command line interface and several other great features. If you feel you’ll be using software RAIDs regularly, I highly recommend inv esting in their software.

The second type of RAID I’d like to discuss is a RAID 5 which performs block-level striping with double distributed parity. This RAID is really the best of both worlds and it’s what I recommend for most pro-sumers and professionals who are serious about their data backup; it’s also a great solution for creative professionals. It mixes the speed of a striped RAID, which writes data across two or more volumes at a time, and the redundancy of a mirrored RAID. I only recommend using RAID 5 in a hardware RAID situation, and most software RAIDs don’t support RAID 5 anyway.

To create a RAID 5 you will need at least three hard drives of equal size and RAID hardware. If you’re on a Mac Pro or Xserve it’s possible to purchase an internal RAID card which would be controlled using Apple’s RAID Utility (/Applications/Utilities). As with Disk Utility, the initial creation of this RAID will destroy the contents of the drives so be sure the drives are blank or that you’ve saved the data from them. The RAID Utility uses a similar format to Disk Utility but includes many of the features of SoftRAID and is overall much more useful.

The other option is to purchase an external RAID system that supports RAID 5. This is often the easiest solution and I see it implemented more often in the businesses I consult with. There are several external RAID solutions that range from very basic to quite robust. I’m personally a fan of Promise RAIDs and the new LaCie RAID offerings (with the caveat that Glyph Technologies is the standard for audio production). Both offer models that range from low-end or just enclosures to high-end enterprise solutions.

LaCie offers a few very basic RAID solutions like the 2TB and 3TB 2big Quadra Quad models. While these both support RAID 0 and RAID 1, they do not support RAID 5. If you’re interested in a LaCie RAID solution that supports RAID 5 I’d suggest checking out the 4TB 4big Quadra Quad Interface or larger. These models support hot-swappable drives for most RAID sets and I personally like their sleek design.

Promise offers several RAIDs and even their most basic model, the SmartStor DS4600, offers the RAID 5 capability (note: you have to buy drives separately). Promise is a company close to my heart as they are an offshoot that was started by Apple in the XServe RAID days. They’re known for having phenomenal Mac support and sturdy, easy-to-use products. If you want an external solution with an “Apple-feel” this is where I’d steer you.

Now that I’ve filled your head with even more ways to create redundant backups, do keep in mind that there is no one right solution out there for back up. There will be a couple more articles in this series to give you even more ideas and if you have a creative and reliable backup solution of your own, please feel free to drop me a line and share; I’ve gotten some great reader responses so far! Thanks for reading!