Creating a Mirror Raid in a MacPro

by Ellen Anon

Every photographer knows how important it is to have backups of your digital files. I have an external RAID system that I've used for a couple of years to store my image files and important documents. When I saw that the new MacPros could be configured with multiple internal drives that could act as a RAID, that seemed like a great idea. I know from painful experience that any hard drive can fail at any time, (but usually only at the most inconvenient time.)

My new MacPro arrived just as my G5 was gasping its last breaths, and as I was leaving to teach a workshop in Pennsylvania followed by a trip to France. I ordered the MacPro with two hard drives, planning to create an internal mirrored RAID set-up. However given the time pressure I was facing, I wanted to set up the computer just enough to enable me to finish preparations for the upcoming course. I decided to just install my applications, drag in some files I had temporarily stored on an external hard drive, and get back to work. Since I didn't see any obvious instructions for setting up the internal RAID, I planned to figure that part out after I returned, when I would have more time. I assumed there must be a straight forward way to do this, although I wasn't quite sure what it was.

So when I got home from France I sat down with the instruction manual, and to my chagrin found very little about how to set up the additional hard drive as a mirrored drive. I went to the Disk Utility, assuming there would be a way to select the additional drive and a button to click to set it to mirror the initial hard drive. That would seem logical to me ... but that's not quite how it works.


2007-08-08 06:57:11
eesh that wasn't very "Mac-like" at all. Thanks for docuemnting this, RAID is going to be very popular in the next year and this will be handy
2007-08-08 08:20:07
You seem to be interested in RAID to protect against hard drive failure and you seem to have less than four drives. Therefore, you want nothing to do with RAID 0!

I suggest becoming thoroughly familiar with the following resources before attempting any RAID setups with your real production data:

Ellen Anon
2007-08-08 08:28:48
You are correct - I meant to say a Raid 1 set up - mirrored.
Dave Camp
2007-08-08 09:38:31
Just for completeness: RAID 1 will help protect from physical hard drive failure but won't protect you from hard drive corruption, so good backups are still necessary. Thankfully, Aperture makes that part easy.
2007-08-08 18:40:18
I already have a Mac-Pro, where can I buy the new RAID Card separate?
2007-08-08 19:25:54
Ellen (and others): FWIW, if you know you want to use RAID ahead of time (i.e. before installing the OS, apps, etc), you can setup a RAID mirror with one drive intially, and then join the new drive to the mirror when you get it.

JO: You don't need an additional RAID card (does apple even sell one apart from w/ the Xserve raids?) to set this up - OSX can do software-based mirroring natively, though you can probably buy any of several types of RAID expansion cards from various online electronics vendors.

Lastly, I would like to echo the corruption issue. I have two pairs of s/w mirrored drives and one pair of h/w mirrored drives and earlier this year, "something" happened to the filesystem on one of the s/w mirrored pairs and I ended up losing half a month's worth of photos (mostly non-work images, thankfully). I really just need more drives to backup my drives to.


2007-08-09 06:07:34
Norby, you are right, for mirrored drives I don't need a raid card, but for a Raid 5 setup you will need it.