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Clear msftres and other GPT 'flags' set by GNU parted
Authored by: KaniS on Mar 07, '08 08:31:06AM
The trick of using Diskutil to mount the msftres partition did not work for me (I tried at least ten times, did all possible software updates and rebooted repeatedly). I could click the mount button, but nothing would happen. The log showed "success" on mounting and that's it. The drive never appeared or became ungrey. Doing a "mount" command from the terminal showed the error "Incorrect super block."

What OSX version are you using? I'm using Tiger with all the latest software updates so I'm guessing the trick will only work in Leopard.

Even though I didn't find a solution, I thought I would post my two-day saga for getting windows working again even though OSX still doesn't see the drive. I'll end with a theoretical way to remove the msftres flag.

After disabling journaling and using gparted 1.8.8 to change the hfs+ partition from 55 to 40 gig and the ntfs from 15 to 30, windows could no longer be selected as a boot option by holding alt. OSX could still see the NTFS partition as read only and all the data seemed to be there. I found you could choose what partition to boot from in OSX, but when it tried to boot XP, it would show the XP logo on black with a progress bar as normal, then eventually show a light blue screen saying "Autochk not found" followed by simply rebooting.

At some point I went back into gparted thinking maybe there's a flag I should set, so I clicked the "boot" flag but didn't click OK. Then I thought I'd better research it before I clicked OK, but it was too late. Simply checking the box makes the change immediately (stupid). Unchecking the box sets the msftres flag which can't be cleared except by checking boot again.

In my research, I learned that osx uses a newer computer firmware API called EFI (Extensible Firmware Interface), and that EFI controls hard drive partitions using "GPT". Windows still uses old BIOS "MBR" to control partitions. gparted had updated the GPT table but not the MBR table, but I found free software called rEFIt that has a partition tool to fix that. Now booting windows didn't complain that Autochk wasn't found, it simply said no boot partition was found (or something like that).

I tried to run a repair install of winxp but when I tried to choose the NTFS partition, it said it was an unrecognized format that couldn't be read. Strange, since it showed up as "NTFS" on the list.

I searched for hours trying to learn how to clear the msftres flag but it seems to be impossible. Finally, as a last resort, I decided to use gparted to just set the "boot" flag so the msftres flag would be cleared and I was amazed that suddenly windows could boot and worked fine. The partition still doesn't show up in osx but I don't care too much about that.

I did think of one theoretical way to get rid of the msftres flag without setting the boot flag. I'm not going to go through the trouble, but I wanted to share it in case anyone wants to try it. has a whole bunch of info about this whole process and discusses how you can partition your drive using the gpt tool. I was able to use free software called "Clonezilla" to copy the ntfs partition to a USB hard drive (I had to use the raw partition mode, not ntfs mode, because the ntfs partition was marked "unclean" until I finally got windows to run its checkdisk). If I then used the gpt tool to destroy and recreate the partition, theoretically I could use Clonezilla to restore the old data to the partition without changing the partition table and maybe I would have things back the way they're supposed to be.

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Clear msftres and other GPT 'flags' set by GNU parted
Authored by: wm on Mar 11, '08 01:32:07AM

Glad you got it working eventually. Definitely don't use gparted to change the partition table, because it doesn't seem to be aware of the GPT/MBR hybrid that OS X uses to allow Windows booting. You should've used diskutil instead (if it would even let you make that change). I'm also a bit surprised that setting the boot flag made Windows boot again and didn't prevent OS X from booting (which is what it did in my case), but whatever.

I think your theoretical solution would probably work, but it might not be worth it for you at this point.

Also, it's possible that I did the procedure mentioned in the hint when booted from a different physical disk from the one that had the partition with the msftres flag set. And yeah, I was using Leopard (10.5.1 at the time).

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