Wednesday, August 18, 2010

How to mark a partition as active (Windows, Linux (Ubuntu, Fedora etc) Unix (Solaris))

All operating systems have the feature of marking partitions as active. I’ll provide helps for Windows, Linux and Unix (Solaris)

Using Windows XP to mark partitions

Ø Enter into disk management (click run from start menu and type diskmgmt.msc).
Ø Right click the primary partition you want to mark as active.
Ø Click Mark Partition as Active and it's done.

Changes will take effect after reboot.

Using Windows Vista/Seven to mark partitions
Click Start Menu> Programs> Accessories. Right click Command Prompt and rus as administrator. Now type

c:>  diskpart 
   diskpart> select disk 0          // list command will list available disks 
   diskpart> select partition 1     // list partition will list partitions 
   diskpart> active                 // mark selected object as active 
   diskpart> exit

You have to provide your own partition number instead of partition no. 1

N.B: If you have Windows Vista in your System be careful. Because Windows Vista Boot Manager have bugs. It may mess up after changing active boot flags.

Using Linux to mark partitions
In Ubuntu/Fedora/Suse CD/DVD you have to use this command

[ ]$ fdisk /dev/sdaX

where X = partition which you want to mark or unmark then use ‘a’ to modify active flag. Press w to store the modification upon completion.

How to mark another partition as active on Solaris
If you can boot into your Solaris OS, boot into Solaris System

Enter following command to modify Solaris Root Partition,

[ ]# fdisk /dev/rdsk/c0d0p0

Depending on your disk configuration this can be c0d1p0 etc
Ø To select "Specify an active partition" press 2
Ø Then Select partition no.
Ø Then press 5 (to save changes and exit).

If you have Solaris but you cannot boot into Solaris and you have Solaris DVD/CD. Then boot from CD/DVD
Ø Select console
Ø In console type the same commands we used previously with Solaris OS.


  1. The linux key for marking a partition as active is 'a,' not 'm'

  2. Thanks. It was a typing mistake.