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I have two hard drives that were set up as a RAID 1 set on a Mac. My Mac died, and I replaced it with a PC running Windows 7. I can't seem to figure out a way to read the data from my disks.

I tried MacDrive, which worked great for non-RAID disks, but it doesn't see either of these disks at all.

These disks are in a Rosewill 8-bay external box, which comes with a utility called SATARAID5. The problem is, that software doesn't run under Windows 7.

Does anyone have any ideas on how to get to this data? I don't care if I end up with a RAID set or not. I just need the files.

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up vote 2 down vote accepted

RAID storage formats (beyond simple mirroring) are typically proprietary -- I'd recommend borrowing a Mac temporarily to read the data off the array.

Oops, just noticed you did mean RAID 1 mirroring! That's odd. The software RAID must have written weird metadata to the drives, which is not typical for mirrors.


One, many RAID cards store meta data at the front of the drive, usually the first 128 sectors of the drive are reserved for the RAID card to use. Information like drive state, time of last boot, size and other information that is important to the RAID card is stored there If, however, the RAID card is not the primary hardware interface but instead a standard IDE port then the BIOS has no way of interpreting vendor specific data. In other words the BIOS looks at sector zero in the boot sequence, tries to find a Master Boot Record, then execute any boot it may find. The problem with this drive is that the MBR is 128 sectors down the drive since the meta data is stored in that area. Knowing this, we can trick the BIOS into skipping the meta data and pointing right to the OS boot record.

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Yes, borrowing another mac would ensure you could get the data off. I agree it is odd that either drive could not be read. I wonder if others have had this issue with os x software raid 1. – Troggy Jan 18 '10 at 2:42
or, maybe MacDrive isn't "smart" enough to understand OS X software RAID 1 hard drive signatures? gcoates have you tried emailing them to ask? – Jeff Atwood Jan 18 '10 at 2:44
I tried that software that you linked, but it doesn't even see the physical drives. (Windows 7 does see the physical drives. They show up in Disk Management. I just can't do anything with them. It shows 3 partitions for each disk, which must indicate that the Mac RAID was doing something special as there was only one RAID partition.) – gcoates Jan 18 '10 at 3:18
It probably sees 3 partitions because it's reading everything wrong as it's shifted by whatever the RAID did. – Marcin Jan 18 '10 at 3:21
I ended up having to borrow another Mac. – gcoates Jan 20 '10 at 3:11

Windows doesn't read Mac RAIDs. It has nothing to do with your version of windows or how you RAIDed them. The way the RAID is setup on a Mac is differently to a RAID setup on a Windows machine, therefore Windows has no clue what to make of it. If anything it may detect that there are two drives, but you won't see that they are RAIDed nor can you access them. It's simply one of those compatibility issues that Windows hasn't addressed.

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Wouldn't it be possible to do a dd dump of the data on one of the mirrored drives in Linux (backing it up on another drive as a file). Then you can use dd again to write everything back to the same drive except you start at 128 in the dump and 0 on the hard drive. Then use a hex editor and Apple's HFS+ tech docs to offset the pointers by 128 sectors. You might have to shift data at the end of the drive also since that is also reserved. The extra space you will have between the end of the data and the reserved data at the end of the drive you can just fit with random data or zeroes. That way you pretty much rebuild it back to how it would be if the RAID software never added those 128 sectors. I'm not sure how much work this would be and what the technological abilities of the original poster are. Being a Software Engineer I would def give it a go if I needed to get the data back. Especially since you don't lose anything by trying since you can always dump everything back to the drive from the original dd dump

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