Now that your raid set is hosed, feel free to experiment with new things. Like a hybrid raid that uses a software RAID 0 to stripe across two hardware RAID 1 mirrors.
First, boot off your Mac OS X install DVD. Open RAID Utility. Use it to create two mirrors. Something like this:
Then, open Disk Utility and play with its software raid features until you make it stripe across those two mirrored volumes you just set up. Like this:
Now install Mac OS X on your new, hybrid, RAID 10, that can handle up to two disk failures (if they aren’t in the same mirror), and doesn’t become degraded in a disk failure scenario, and has very fast rebuild times. win-win-win.
Now, to go out and buy a big external drive to run Time Machine with…..
So, over a year ago I bought a Mac Pro with the Apple RAID Card. I was really disappointed to find that it didn’t support RAID 10, which is a form of nested raid whereby a RAID 0 (a stripe) is laid across two or more RAID 1’s (disk mirrors). Apple’s implementation allowed for RAID 0+1, which is the other way around: a mirror of two stripe sets usually. That is a much inferior setup, because if any single disk fails, then both disks in that striped pair are out — meaning half your mirror is down. In a RAID 10, you can lose a disk without penalty. You can even lose two disks as long as they aren’t on the same side of the stripe (i.e. aren’t both in the same mirrored pair) — again, without penalty.
In light of Apple’s foolish RAID 0+1 option on their raid card, I opted for RAID 5 instead. Against my better judgement. But with faith in Apple. AND IT FAILED. I lost one disk last week. I promptly shut down my machine in an orderly fashion (because SATA isn’t hot-swappable; only SAS can do that in a Mac Pro). I replaced the failed disk with an identical cold spare that I had on hand (holla). I booted up, I started the RAID Utility program, I marked the new disk a hot spare, the Utility added it back into my raid set and began rebuilding the array, which, of course, was in a degraded state. The rebuild finished — all lights were green — the RAID Utility told me that my RAID 5 set was “Viable (Good)”. Viola! Right?
Wrong. I rebooted the machine and it never came back up! I booted off the Mac OS X DVD and verified the volume in Disk Utility. Fail. Inaccurate record count. Unable to mount the volume. I re-open the RAID Utility and attempt a VERIFY procedure on the raid set. Fail. It won’t even start the routine.
In the end, I lost the entire 1.2 TB RAID 5, with about 600 gigs of my precious data on it. I had backups of all the most recent things, but lost some music, and quite a lot of movies I’d ripped from NetFlix DVD’s and — because of their size mainly — hadn’t backed-up onto my too-small external drive. Yeaaaah. *sigh*
Yep, it’s true. And why not? The economic conditions are perfect. It just makes sense, and so I took the plunge. I found the house below and got it under contract less than two days later. This past week I compared mortgage lenders and finally decided to go with Bank of America on a 30-year fixed rate FHA mortgage at 4.75%. I uploaded the photos to my Google Picasa album. Check it out:
