I put more than 4 partitions in an MBR table...

Lenios · January 12, 2017

Hello all,

I was trying to set up a triple boot system (Windows 10, Linux Mint, Remix OS) as an upgrade from the current dual-boot system I run.

I'm aware that an MBR partition table can only have 4 primary partitions; however, I have somehow accidentally created 5...

Should I be concerned that this might corrupt my files on this drive? There's no problems with files so far, but I am worried that they might appear in the future.

It does appear to have caused an issue elsewhere though.

When booting the computer, I get an error which says 'Unknown Filesystem', and I am sent into GRUB rescue mode.

This is what I am typing into the rescue mode command line to make the computer boot:

>set boot=(hd0,msdos6)
>set prefix=(hd0,msdos6)/boot/grub
>insmod normal
>normal

After entering the last line above, the computer then shows the normal GRUB menu, and I can choose to boot into either Windows or Mint (I haven't set Remix up yet due to this issue)

I was wondering if there was a permanent fix to this issue, so that the GRUB menu would show up straight away as normal?

Finally, is it safe to delete the 5th partition which has caused the issue, or will editing the partitions further cause more issues?

Any advice on this would be greatly appreciated. Thank you.

samcool55 · January 12, 2017

I'm not experienced but i do know that you can add logical partitions, afaik you can't boot from a logical partition (it has to be primary) but once you get the boot stuff figured out it should be good to go.

So if i'm right (which might not be the case) as long as every OS has their boot stuff on a primary drive, you should be fine. But then again that's all i can remember from stuff i learned a few years ago.

Lenios · January 12, 2017

So, update (yes, already).

My windows partition appears to have died, although I've not changed anything. That's 1.8Tb of my 2Tb HDD inaccessible as far as I can tell. Windows automatic repair tries to run and says it can't fix the issue.

It had some files on it, but none of them are a major loss.

Mint still boots fine though, although it won't mount the damaged partition either.

Looks like the computer will be taking a trip to my local repair shop

Unless anyone knows of a magic fix?

Suppose that answers the 'will my files get corrupted?' question.