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AFAIK, there can not be more than 4 primary partitions in one HDD because of the size limit of the MBR.

I've installed Ubuntu 12.04 and Windows 7 together.

Here is the screenshot captured from Windows 7 Disk Management Tool (built-in)

View it in original size

But, how can "Primary Partition" be located in "Extended Partition"?


  • /dev/sda8 is for SWAP
  • /dev/sda9 is for '/boot'
  • /dev/sda10 is for '/'
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up vote 6 down vote accepted

You don't have primary partitions within your secondary partition. That is impossible.

Nor do you have the EFI partitioning scheme. That doesn't have MBR-style secondary partitions.

What you have is a bug in Microsoft's Disk Management tool, introduced in Windows NT 6.0 ("Vista") and still present in Windows NT 6.1. Although the partitions are secondary partitions, because they have a partition type code that Microsoft's Disk Management tool doesn't understand, it erroneously says "Primary Partition" and uses the colour for primary partitions.

Use a partition table reporting tool without this bug, and you'll soon see that the impossible is not happening on your computer. ☺

Further reading

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I think there are a couple of issues here.

From what you have written, there is no "Primary Partition" in an "Extended Partition" from what you have provided above. What you have is a "root" partition in an extended partition.

It is possible (and common place) for the root partition to be anywhere on the system. I believe that in this case, all that is needed is that GRUB (or whatever bootloader you are using) recognizes the partion and allows you to boot from it.

For more details on using Grub to boot off an extended partition, look here.

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Winpart explicitly labels the two dark-blue partitions inside the extended partition as Primary Partition. One, including me, would expect only light-blue (i.e. logical partitions) partitions inside a extended one. IMHO there is no partition flas for primary, so how does winpart identify these partitions as primary? – mpy Feb 5 '14 at 9:08
Good question. What does (Linux FDISK) make of the structure though ? Also, is it possible you are using a GPT/GUID partition rather then an MBR one ? (I confess to not knowing as much as I'd like about GPT yet) – davidgo Feb 5 '14 at 9:17

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