First you need to resize your windows 7 partition and create a new partition for installation.
If you are more familiar with windows you can do it from windows disk management utility or using
gparted in ubuntu.
Take Backup before doing anything else. Also create recovery media s for restoration. You might loose ability to use recovery partition in easy way
Run prompt by pressing Win + R. Type
diskmgmt.msc to open up the management console.
- Right click on
C: drive containing Windows 7 and choose shrink. Follow the wizard to shrink it as much as possible.There will be unallocated space now. Close the window.
- Now to create an extended partition. (There difference between primary partition and logical partition,to avoid multiple OS installation problem we are creating this) To do so, press Win, search for
cmd. Now right click on it and choose run as administrator.
In console type
diskpart, when diskpart changes the prompt. type following commands one by one
select disk 0
create partition extended
- Now again open disk management by following step 1.
- Right click on the unallocated space and select
New simple volume, change the amount of space you want to be in ubuntu drive. choose do not format this drive in the next step. We will use this volume as for ubuntu installation.
- The rest of unallocated space you can create as many parition as you want by following the sixth step and formatting to ntfs (if you want them to use in windows).
A good partition tutorial is here if you are in any doubt
Now get back to ubuntu installation:
- Boot up using the live cd/usb. Now choose
something else option.
- Gparted tool will open with your current disk configuration. Figure out the space you reserved in step 6 for ubuntu. Click on that, choose
delete. It will became free space.
- Creating swap space: click on the free space , the click on
add. Now select file system as
SWAP and size as 1GB (swap space is alternative to RAM, depending upon ram size you can decide )
- Creating the ubuntu disk: Now after adding swap space, there will be free space. Click on that, again click add. This time choose file system as
ext4 and for mount point
/ from the drop down.
A reference image of my system :
Now go forward with your install. Ubuntu and windows duel boot will ready in minutes. :)