Quote:

The article had three drives in the RAID1 array. Since RAID1 is mirroring, I've never seen 3 drives in a mirrored array. So I was wondering if one drive is actually mirrored to the other 2 in the array.


RAID1 arrays of four drives are actually quite common in the commercial systems I work on here. These people are really *paranoid* about their data, and don't want it ever to be exposed with no hot backup online. With only 2-drive RAID1, when one drive fails they would then be without a live backup until a new drive got "built" back into the RAID1. With three drives, no such problem. With four drives, even safer.

Quote:
So it sounds like this...someone correct me if I am wrong:

- All writes to the boot partition are mirrored to two other drives.
- If any one of the three drives fails, the fourth will automatically join the array so that the first partition is still mirrored to two others.
- If the first drive fails, then the system would boot off drive two which would then be mirrored to drive three and four.


Yup, that's the idea. Many modern BIOSs will automatically do that last step (boot from first available drive) in particular.

-ml