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Resize an Existing Partition
With Microsoft's Disk Management Tool.

The introduction of the resize feature in recent versions means we can safely
release disk space for new partitions by non-destructively shrinking an existing partition.

Modifying or moving existing partitions can be a risky and time consuming business and in general it is something that should be avoided. The exception to the rule is the relatively simple procedure of increasing or reducing the length of partitions to change their ending point on a hard drive. This is the only major operation that Disk Management can do and it may seem a bit limited, but with a little thought or with the aid of some backup or cloning software it can be all that is required to safely and completely reconfigure a hard drive.

confused guy iconDo You Know Enough? There are situations where resizing a partition may not be useful or desirable. The classic MBR partitioning scheme has a limit of only 4 primary partitions, so making space for a fifth primary would be pointless. Please make sure you at least know the basics before you begin. info iconA Beginners Introduction to Partitions.

Know your Alignments. The later versions of Disk Management will make and resize partitions to the new 4K alignments, so resizing a classically aligned partition will result in one that starts with the old rules but ends on the new. This in itself may not cause any issues, but using an opposite standard of tool from existing partitions should still be avoided.info iconWorking With the New Partition Alignments

RAW and Dynamic.
Only NTFS or RAW partitions can be resized but be aware that RAW and unformatted partitions can contain such things as database files and shrinking them can be data destructive. Likewise Dynamic Disks and their partitions can be damaged by resizing and is outwith the scope of this guide. Please refer to Disk Management's own Help file if you want to adjust dynamic volumes. info iconDon't be Dynamic


Shrinking a Partition

For a primer and details on how to start the Disk Management tool please refer to the first article in this series.

Fig: 1
disk management screenshot
The computer shown here in fig:1 has only one hard drive which has a small factory configured recovery partition and the main Windows-7 partition from where the Disk Management utility is being run. We can shrink the Windows partition even though we are currently booted into it, but we should never just assume it will be safe to do so. Our example here is basic and straight forward with only two partitions but some factory configured machines can be somewhat busier and perhaps beyond modifying. It should go without saying that you must have backups of personal data and at the very least the ability to restore a machine to a factory state from boot disks. If you have a cherished and required operating system that you would rather not loose and you don't have the means and the backups with which to restore it, well.....


Fig: 2
disk management screenshot
If you are not dealing with a factory configured machine or you have researched how any recovery system works and you are confident there are no surprises ahead, or you have simply thrown caution to the wind, then proceed by right clicking on the partition you wish to change (fig:2). It will become shaded to tell you that it is the partition in focus and you will get a pop-up menu of options. Here the Extend Volume option is grayed out because there is no free space after the partition to extend into. Click the Shrink Volume option and you should get the message box shown in fig:3.


Fig: 3
disk management screenshot
It could take seconds or minutes before you get to the next box shown in fig:4.

drives iconIf you have more than one hard drive you need to be extra careful you are going to be altering the drive you intended.  info iconOut of Order.
advanced format iconDo you know the Format of your drive and the alignments to use? info iconDrive Format.
drive style iconDo you know if you are working on an MBR or a GUID partitioned hard drive?
info iconDetermine Your Style.
disk recovery iconDo you have a factory installed recovery system that could be broken by any partition work? info iconNo Restore
raw iconUnformatted or RAW partitions can still hold data so if you come across one you should not just assume it is empty.
info iconWhat's the Raw Deal?
caution iconPlease read our full advice and cautions page before you start making fundamental changes to your computer.
info iconRecommendations.
Fig: 4 wizard screenshot
The highlighted numbers and those in the number box directly above will both show the maximum free space you could release - 275080 MB which is 275gigs. If you were to go ahead with this setting you would end up with a Windows partition resized down to the size shown in the last number box, which here is 20058 MB. - that's approx 20gigs.

The Windows-7 operating system in our example here is very lean and only occupies 13gigs of the partition and so we could if we wanted shrink things down to the 20gigs we have been offered. The possible size we can shrink down to will be dictated by among other things the overall amount of data that is on the partition, but it can also be affected by where that data is. If for example we had some immovable file like the swap file right in the middle of our partition then the available shrink space we will be offered will not go past that. In our example that would mean we could only resize the Windows partition down to a minimum of about 145gigs. If you encounter this problem there are some steps you can take....   Three - Outside - Links.

wizard screenshot
To set the new desired size for the partition alter the numbers in the white box until the after shrink number in the bottom box shows the figure you want. Here we are going for 80gigs so subtract 80,000 from the before shrink number shown at the very top and type the answer in. You can then use the up/down arrows to fine tune the numbers. In our example (fig:5) we went for precision and set the new partition size to 81920, which is 80gigs in computer hard drive terms. (80 x 1024 MiB) When happy, push the Shrink button.

Fig: 6
disk management screenshot

The resize operation may take only seconds or depending on how much data there is to be defragged and moved into the new space it may take a while. Our example here now has 208gigs of free space that we can partition up and use for other operating systems and/or a data partition, or for clones of the current Windows-7 install.


Extending a Partition

To extend an existing partition it is necessary to have unallocated or free space immediately after it on the drive to expand into. Windows Disk Management can only move the ending point of a partition towards the end of the drive, you can’t extend from the start of a partition towards the front of a drive.

Fig: 7
diak management screenshot
Our drive in fig:7 has the necessary empty space that will allow us to increase the size of the Windows-7 partition. Right click on the partition and select the Extend Volume option and you will get the first Wizard dialog box shown in fig:8 where the only option is to click Next. This will bring up the main dialog box where we select our options.

Fig: 8

The hard drive of the partition you selected will be listed in the right hand window and in the majority of cases the left hand window will be empty (fig:8). If however you have other hard drives in the machine and you also have the correct circumstances then you may be given the option to merge free space from other hard drives to the partition you have chosen to expand. If you do have other drives showing in the left hand Available window (Hover Here) you will have the option of adding them to the Selected window. Please be acutely aware that this is a highly undesirable thing to do unless you are an expert on Dynamic Disks and understand the consequences of this action. For most of us the Next button might just as well read 'Destroy all Data on Selected Disks' because those disks will be converted to be Dynamic, which will be beyond most peoples' ability to reverse without wiping the drive/s and starting over.

So make sure that only the hard drive of the partition you want to extend is listed in the Selected window and then you can focus on the only option here that concerns us. The bottom white numbers box will show all of our available free space, but if you don't want to use all of it then change the number to the amount of MB you want to add to your selected partition (fig:9). We are wanting to increase our 80gig partition to 100gigs, so we enter 20,000 in the box

Fig: 9
wisard screenshot
20gigs is 20,000 MB, or to be pedantic it is 20x1024 MiB, so if you want to see round numbers in Disk Management you would enter 20,480. Clicking next will bring up a summery of changes and the chance to step back and alter them.

Fig: 10
disk management screenshot

The finished result is that our Windows-7 partition has increased by the 20,000MB to make it around the 100gigs mark. If we had entered 20,480 it might show in Disk Management as exactly 100.00 GB, but these nice round gig numbers often don't show in Windows itself, so chasing them in Disk Management can be futile.


More Adventurous Modifying and Moving of Partitions.
There are plenty of third-party partitioning tools that can auto-magically juggle and resize partitions almost any way that takes your fancy. We are not an advocate of most of this because it is risky and can often be much more time consuming than other safer ways of doing things. It can also remove any real need on your part to know and understand what you are actually doing, which is always undesirable.

To remove the recovery partition for example from our drive shown above and then move the Windows partition to the beginning of the disk, the first thing we would do no matter which way we planned to proceed would be to make our back-up of the Windows partition. We would make at least two back-ups by cloning the entire partition into the unallocated space we have created and also to another internal or external hard drive. Once we have tested that the new clones were bootable and usable we would delete the recovery partition and the original Windows partition and then clone Windows back to the position we wanted at the start of the drive. info iconSee our Best Practices guide for working with existing partitions.





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