A dual boot installation alongside Windows is one of the best ways to try a new operating system, whether it is a newer version of Windows or a Linux distribution. With dual boot, every time we start the PC, we will get to choose which OS we want to load. However, before we begin a dual boot installation, it's a good idea to prepare Windows, to make sure the installation goes without a hitch.
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Create a full Windows backup
Dual boot installations are usually safe, but any work with partitions runs the risk that something could go wrong. That could potentially mean losing our original Windows installation, along with all the files and programs.
So, it's best to do a full Windows backup, as a precaution, using AOMEI Backupper or a similar imaging software.
This way, should anything go wrong during the dual boot installation, we can restore the original Windows in just a few minutes, with all the files, programs, and settings at the time of the backup.
For the full procedure, step by step, check our detailed guide:
How to prepare Windows for partitioning
Unless we have a second hard drive to install the new operating system, we need to shrink the Windows partition for a dual boot installation, to make space for the new OS's partition or partitions.
Before we shrink the Windows partition, we must make sure there are no file system errors, and it is also a good idea to defrag our drive.
Prepare Windows 8.1 / Windows 10
On Windows 8.1 and Windows 10, we just need to right-click on the hard drive and select "Properties"...
On the "Tools" tab, we first run the "Error checking" app.
Even if Windows claims we don't need to check a drive, we should do a scan, as a precaution.
The scan should only take a few seconds. If it takes longer than that, it means that the file system had more serious problems than Windows realized.
After a successful scan, and only if we have an HDD drive, it's a good idea to do a full optimization and defragmentation from the Tools tab.
The optimization feature is not available for Solid-State Drive (SSD) disks.
Prepare Windows 7
The choices to prepare Windows 7 are the same as in Windows 8.1 and Windows 10, but the names are slightly different.
So, again we right-click the drive we are interested in, and select "Properties".
We run the "Error-checking" app on the "Tools" tab.
The first option, "Automatically fix file system errors is enough. The second option will scan the whole disk surface; for large disks, it can take hours.
Windows 8.1 and Windows 10 can do the scan live, but Windows 7 need to schedule the scan for the system partition.
On next reboot, the scan will take a few seconds, usually less than half a minute.
After that, we go back to the "Tools" and select Defragmentation.
Windows 7 allows us to defragment an SSD, but we really shouldn't. Defragmentation has no advantages for SSD drives, and it does a lot of unnecessary writes, which shorten the disk's lifespan.
Partitioning
If we want to install a newer version of Windows on dual boot, such as Windows 10 Technical Preview, Windows installation won't allow us to shrink the current Windows partition, to make space for the new OS. We need to do it manually on our current version of Windows.
It's different with Linux distributions since most of them support automatic resizing of the Windows partition during the installation. Still, it's always safer to handle NTFS from within Windows. After all, Linux support of NTFS isn't exactly official, and some distributions don't support NTFS at all during the installation.
To create the partitions we need, we just press the Windows key + R and type:
diskmgmt.msc
On the disk management console, we right-click on the partition of our choice, and select "Shrink Volume".
For most Linux distributions, 15GB of space is more than enough for a dual boot configuration. So on the "Enter the amount of space to shrink" we select 15*1024=15360MB.
To dual boot a newer version of Windows, we should give at least 50GB(51200MB) for a basic installation. Of course, it depends on how many programs we intend to install on the second OS.
For a Linux installation, it is also a good idea to create the three main Linux partitions: root "/", "/home", and swap, which is the equivalent of Virtual Memory in Windows.
So, we right-click the unallocated space, select "New Simple Volume"...
...and give 10240MB (10GB) for root "/".
We don't need to assign a drive letter or drive path. After all, it will be formatted to a Linux-only file system, such as Ext4, and Windows won't be able to read it anymore.
We also don't need to format the volume.
We repeat the procedure to create partitions for /home, where 4096MB is enough, and Swap, which will take the slightly less than 1GB left.
The last two partitions are of a different color because they are extended partitions, not primary. A disk with MBR partition style supports only four primary partitions, but up to 99 extended.
If we shrunk the Windows partition more than 15GB, we should give root "/" 10-15GB, swap 1-2GB, and the rest to the "/home" partition, which will contain all the files and application settings for every user.
Disable Fast Startup (Windows 8.1 and Windows 10 only)
Have you noticed that Windows 8.1 and Windows 10 have a lower boot time than Windows 7, on the same PC? This happens because of the fast startup.
When we shut down the newer versions of Windows, part of the system is hibernated, with specific system data written from the RAM to the hard drive.
The next time we boot Windows, the hibernated data is restored to RAM, shaving off a few seconds as opposed to cold boot.
The Fast Startup feature might be a smart idea to lower boot time, but it can create problems on dual boot. It could lead to data loss in Windows. So, we should disable it, just to be on the safe side.
How to disable Fast Start in Windows 8.1
To disable this feature in Windows 8.1, we just need to go to the start screen, and search for "Power Options".
There, we click on "Choose what the power buttons do".
To unlock the setting, we click on "Change settings that are currently unavailable"...
and then we can uncheck the "Turn on fast startup".
How to disable Fast Start in Windows 10
Windows 10 have messed up with the system options, by having some options at the settings screen, some at the control panel, and some on both.
The fastest way to disable Fast Start is right-clicking on the start menu button, and selecting "Power options".
From there, we click on the "Additional power settings" link.
After that, the procedure is identical to the one on Windows 8.1. We click on the "Choose what the power button does" link...
To unlock the setting, we click on "Change settings that are currently unavailable"...
and then we can uncheck the "Turn on fast startup".
I can't find the "fast startup" option
Some systems with Windows 8.1 or Windows 10 will not have the fast startup option at all.
Those systems don't support fast startup, so there is no need to disable it.
Now, we are ready to install the other OS in dual boot
Whether it is Windows 10 Creators Update, an insider track of Windows, Ubuntu, Elementary OS, or any other Linux distribution, once we prepare Windows for the dual boot installation, there is a much lower chance that something could go wrong.
After having prepared our Windows installation for dual boot, downloading and created an installation medium for our second OS - be it Linux or Windows, it's just a matter of changing the boot order and beginning the new installation.
If you have any questions regarding dual boot or had any trouble with your installation, let us know in the comments below.
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Thank you for this article! I wish I had found it a week ago before I installed Linux on my old HP Slimline without dual boot or creating a Windows system repair disk. I had second chance with my HP TouchSmart 300; installed Linux Ubuntu 16.04 alongside Windows 10 (upgraded from the factory Windows 7 install) using your process. Dual boot is working! I would have liked to follow the best practice for partitioning that you described, but you are missing a step for newbies. In Disk Management, when you create the new partitions how do you specify primary vs. logical partition and root, home, and swap? Following the steps as currently outlined, I created 3 new unnamed logical partitions. Then during Ubuntu install it could not identify a root partition. The Ubuntu installer offered a Disk Management menu similar to Windows 10 where I could have possibly modified the partitions, but I could not figure out how to do so. In the end, I went back into Windows 10 Disk Management, deleted my new partitions and allowed the Ubuntu installer to create default partition setup in the unallocated space.