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Creating a Mirror Raid in a MacPro
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.
In fact what you have to do is first boot up from the Install DVD that comes with the MacPro. Then select Disk Utility from the menu bar at the top. Next select the RAID tab, select both drives and then click to create a mirrored Raid from them. You can select options for Block Size and whether to have the mirror occur automatically (which is how I want it to behave.) But when you click OK, a warning dialog appears that cautions that all data on the drives will be lost. Ouch! That's not what I had in mind at all.
The dialog doesn't explain a work around. I really didn't want to have to reinstall all the applications and recreate all my settings again. So what I did was to create a Disk Image of the drive containing the applications and data, and opted to save it on my external hard drive. (To create a disk image of a drive, launch Disk Utility, select the drive in the left hand column, and then click on New Image.)
Next I proceeded with setting up the two drives as a mirror RAID. I then proceeded with the installation of the OS from the DVD. After the computer launched, I dragged the Disk Image onto the desktop and then double clicked to open it. I opened Disk utility and this time I clicked the Restore tab. I set the opened Disk Image as the source (if you leave it as a DMG you'll get an error message) and the new RAID as the destination. A little while later all my applications were installed and able to be launched, and my data was just where I had put it. Whew!!!!
Yes, it would have been better and easier to create the mirror RAID before I installed applications, etc, but sometimes that's not possible. After all, some people may buy a second drive later and want to use it as a mirror backup. They certainly won't want to lose all the information on their main drive. A few months from now when leopard is released maybe I'll prefer to use Time Machine on an external hard drive, but for now I like the security of having a copy of my hard drive.
There was another amusing error message I encountered along the way. When I tried to install Aperture on the MacPro, it cautioned that the computer didn't meet the minimum requirements for Aperture. I had to download v1.5 in order for Aperture to know that it really can run on a MacPro!
Maybe there was an easier way, but in any case, I hope my experience helps someone else!
Note:: Timing is everything in life. Apparently Apple realized the omission and created a RAID configure option for the new MacPros. David Schloss just blogged about it this morning on our sister site, AUPN (www.apertureprofessional.com.)
Comments (7)
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
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:
http://en.wikipedia.org/wiki/RAID
http://en.wikipedia.org/wiki/Standard_RAID_levels
You are correct - I meant to say a Raid 1 set up - mirrored.
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.
I already have a Mac-Pro, where can I buy the new RAID Card separate?
Thanks,
JO
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.
-/\/
Norby, you are right, for mirrored drives I don't need a raid card, but for a Raid 5 setup you will need it.
JO