Windows 7 - Can't mark OS partition as Active

Pericles · 11-13-2010

Greetings,

After formatting my new laptop, I deleted the manufacturer recovery partition, the 100MB partition, resized, merged, created a new Data partition, etc. However, I cannot mark my OS partition (C

as Active; I can only make my Data (D

partition Active. Please advise.

Kari · 11-13-2010

I'm confused; your screenshot clearly shows partition C: being active.

Orbital Shark · 11-13-2010

Hi,

Setting an Active partition is used when you have multiple OS's installed and wish the system to 'Default' to a particular OS when booting up.

I've seen occasions where setting the only OS partition to active can mess up the MBR and a repair is required which resets it back to it's default state to allow booting.

update: It looks as if the 'Active' partition is the first in the string (the string starting from left to right) of partitions from the same disk.

OS

Bare Foot Kid · 11-13-2010

Hello Pericles.

There can only be a single active partition per Hard Disk Drive (HDD) as that's the flag that tells WinRE (Windows Recovery Environment) where to repair startup errors or where to create new boot files; do not mark D: as active, it will cause the OS not to boot; have a look at this tutorial at the link below for more info.

Startup Repair - Run 3 Separate Times

pip22 · 11-13-2010

Orbital Shark said "Setting an Active partition is used when you have multiple OS's installed and wish the system to 'Default' to a particular OS when booting up"

Having a partition marked "Active" is not just used for dual-boot configurations. Regular, single installations require an active partition too.

mjf · 11-13-2010

Quote: Originally Posted by Pericles

Greetings,

After formatting my new laptop, I deleted the manufacturer recovery partition, the 100MB partition, resized, merged, created a new Data partition, etc. However, I cannot mark my OS partition (C

as Active; I can only make my Data (D

partition Active. Please advise.

Did you make recovery disks before doing this?
As stated your OS partition is already active. Assuming your OS is ok then the Bare Foot Kid advice is your next step.

Just curious - why did you do this?

whs · 11-13-2010

It looks to me as if you deleted your MBR when you deleted the 100MB partition and now you cannot boot. The fix is as Bare Foot Kid says. Marking a partition active without a MBR on that partition will do nothing for you.

mjf · 11-13-2010

In your case follow the tutorial carefully. You will almost certainly need 3 repairs assuming your OS is still in tact.
Your MBR on the first sector of the HDD will need it's partition table updated which includes marking the new active partition entry. (One repair)
Your PBR (partition boot record), boot manager and BCD store used to be part of your 100MB partition. They now need to be in c: requiring the 2 extra repairs.
Hopefully then Windows will load.

Pericles · 11-13-2010

My computer boots perfectly fine as is. Is there any reason to do all this? I only use a single OS.

whs · 11-13-2010

Quote: Originally Posted by Pericles

My computer boots perfectly fine as is. Is there any reason to do all this? I only use a single OS.

Now I am confused. In your disk management picture, C is marked as active. And if it boots, what seems to be the problem? We thought you had a boot problem.

Windows 7 - Can't mark OS partition as Active

Can't mark OS partition as Active problems?