Microsoft will shortly begin releasing the final build of Windows 8 to MSDN and TechNet subscribers online and thousands of people, including myself will install it and begin using this exciting new OS properly. Are you going to install it on a computer with more than one physical hard disk though? If so, beware drive 0!
When Windows is installed it creates a special boot partition called System Reserved on your computer. This partition, which was 100MB in Windows Vista and Windows 7 but has now been increased in size to 350MB in Windows 8 to accommodate new rescue and boot tools, is always placed on the first physical disk plugged onto your motherboard. This disk is called Drive 0.
It appears in the list of hard disks that you can install Windows 8 onto in the installer, as you can see in this screenshot. The second physical hard disk in your computer will be called Disk 1, the third Disc 2 and so on.
In computers built by Original Equipment Manufacturer (OEM) companies such as Dell, Samsung or HP the current copy of Windows will already be installed on Drive 0 with the System Reserved partition, but if you built your own PC or bought it from a smaller company it may not be.
The problem is caused by the fact that when you’re plugging the SATA hard disk cables into your motherboard there’s usually very little way to know which socket is drive 0. The upshot is more serious however. If the hard disk you want to install Windows 8 onto is actually Drive 1 or Drive 2 then you will never be able to remove the physical Drive 0 hard disk from your computer without rendering your copy of Windows unusable.
Also, if you want to create a system image backup and Disk 0 already has a partition at the beginning of the drive space, the System Reserved files will be placed in this partition. Should this be a large partition containing files for example, then you will also have to include this entire partition and all its contents in your system image backup. This will make for a very large backup file and also restore an earlier copy of all your files when you restore Windows. Wiping out newer files completely.
So how can you avoid these problems? One way is to physically unplug all of the hard disk from your computer other than the one onto which you want to install Windows 8 before you install the OS. This forces the installer to see the only available hard disk as Drive 0, problem solved.
It’s not always possible to physically unplug hard disks however, you might have a twin-hard disk laptop or all-in-one PC for example. Here you need to be careful when choosing where to install Windows 8, to create a drive for it on drive 0 in the disk drives list (when choosing a custom install).
My best advice is to completely delete the existing System Reserved and Windows partitions and have the Windows 8 installer create new ones. This means you will get the maximum benefit brought by new repair feature’s that require the larger 350MB system reserved partition and you will also get around subtle changes that come with Windows 8 installations on newer computers containing UEFI firmware.
Overall though my advice is to take care when installing Windows 8. You might need to wipe some partitions completely and restore everything from a backup after the installation is complete. You do have all your files backed up after all don’t you!?
With Windows 8 installed on Drive 0 in your computer you can be sure you’ll enjoy trouble-free use thereafter, and I sincerely hope you enjoy using Windows 8 as much as I will.
“This partition, which was 100MB in Windows Vista and Windows 7 but has now been increased in size to 350MB in Windows 8 to accommodate new rescue and boot tools, is always placed on the first physical disk plugged onto your motherboard. This disk is called Drive 0.”
Now I’m afraid to upgrade for fear of losing all my precious data! There one thing I don’t understand though… I have 2 HDDs and want to install Windows 8 on the 2nd one. The first is partitioned and contains data. How can the Windows 8 installer possibly create the 350 MB partition on it? Will it automatically shrink the existing partition (first one) on the drive to make space? How is this possible, that it will take it upon itself to mess with my partitioning scheme?
Hi James, the Windows 8 installer is very careful with upgrading so you won’t have any problems with the System Reserved Partition.
As your data is on the second hard disk though I would always recommend deleting the Windows partition and performing a clean install to get the best experience.
Thanks Mike! I’ve still got some small doubts though, hope you can clear them up for me?
Case 1) On one PC with single HDD, I have Windows 7 on the first partition and 2 more partitions for data. No System Reserved partition as drive was partitioned before Windows install. I will use Windows 8 setup to format (not delete) the first partition. Now what will setup do? Will it install in first partition and not create any System Reserved partition, leaving data partitions untouched?
Case 2) On another PC with single HDD, I have a 100 MB System Reserved partition, then Windows 7 on second partition and 1 more data partition.
i) If I format the 7 partition with setup and install 8 into it, will I end up with 100 MB partition, then Windows 8, then data, with no 350 MB System Reserved partition? If so, won’t the old 100 MB System Reserved partition affect the new OS?
ii) If I delete both the 100 MB System Reserved partition and the 7 partition, leaving only blank unallocated space at beginning followed by the data partition, what will happen? Will I end up with new 350 MB System Reserved partition, then Windows 8 partition and finally data partition untouched?
Yesterday the Win8 installer destroyed my Win7 system partition. This is how it happened:
Am using BING as boot manager and tried to hide Win7 partitions from Win8. Win8 installer considers hidden partitions as unallocated space.
Did not think about possible consequences and installed Win8 on Drive 1. However the 350MB system reserved partition was created on Drive 0, right on top of my Win7 partition!
Yes, I had fresh disk images on hand, but it took me a while to find out why my old Win7 would not boot.
Hi there, my Samsung laptop cant boot a OS from disk 0 and windows has assigned disk 0 to my hard drive, disk 1 is assigned to 7gb partition. At the moment i am unable to boot my main computer because of the reason.
Any advise?
Hi Louis, It sounds like the system reserved partition for Windows is on the wrong physical disk and needs to be moved. This is detailed in my new Troubleshoot and Optimize WIndows 8 Inside Out book on page 454 but I’ve not written up an article about it yet. A search online can find some solutions though. I’ll get an article written soon but hope you find one soon.
Hi James,
Apologies for taking so long to reply, it’s been really busy here.
Case 1) Windows 8 setup won’t change your drives but you will lose access to some functionality that can be used to repair an installation if you don’t allow Windows to create a system reserved partition, you may also be unable to create a system image backup. It won’t touch your data partitions.
Case 2) The Windows 8 installer will keep the 100Mb partition but ideally you need to delete it and have Windows 8 create its full 350MB one so you can get full access to the rescue and image backup features.
Mike
I wish i had read this posting a week before.
I installed windows 8 to my new ssd this week, and guess what happened?
My existing hdd was on drive0 and ssd was on drive1, and i chose ssd fo clean set up.
My existing windows 7 partition was overwritten with system reserve of windows 8.
Too bad, but since i had separated data files, it os okay with me.
My question is, with system reserve volume on hdd and windows 8 on ssd, will it slow down the boot up or some system speed when compared to having it all on ssd?
I can’t understand why anyone would want to install Windows 8, I would like to to know if I safely can remove all the partitions created by Windows 8? I got six partitions on my new PC that comes with Windows 8.
I installed Win8 before seeing this article and now my recovery drive is low on disk space. I assume this is a result of the partition changes mentioned here.
Now, I need to know how I can relieve some space (delete unnecessary files) on my Recovery Drive. Here’s what it looks like today:
Data File Backup: 6.65GB
System Image: 0bytes
Other Files: 8.35GB
Free Space: 1.34MB
Total Size: 15.00GB
Any advice?
I guess that I am the newest member of the “Windows 8 screwed up my computer” club. It looks like my boot sector has been destroyed on my system and I get the BLUE SCREEN OF DEATH. I have mixed sata and ide in my system. My Seagate ide drive is a boot drive. I’m glad that I paid the extra $13 for the DVD copy of Win8 because that may be the only way that I get this computer working again.
Dan
well i guess im a new member of windows 8 problems….i have a dell inspiron…bought the refurbished computer from ebay…all i had to do was add the operating disk…we got win 8…well now i cant get my start page to come up and on top of that…now its saying it cant find the partition…at a loss please help me .
I installed Windows 8 2 weeks ago on a brand new system with 3 SATA drives. I chose to install windows on my solid state drive (128 Gb) for speed. My other SATA drives (1Tb) in the drive 0 position (I guess since it shows “system Reserved”) and second drive (2 Tb) shows files as I load them from my old XP drive in a USB adapter.
My system shows the system reserve, and then the properties function shows that only 380 Mb remain on the drive out of the 1 Terra bytes.
Somehow (I am in a fog about it) I think I set up a “shadow drive” to allow full recovery, but if I did this I don’t remember exactly how.
Is there any way to free up the other 998 Gb on that drive?
Thanks
This happened to me, when I originally installed I thought it was weird that it wasn’t putting the small recovery partition on my primary drive. A few weeks later I’m updating my secondary only to find out that the OS won’t boot and I’m pretty much hosed unless I format.
Why would they change it to be this way in Windows 8?
Hi, Mike. Thanks for the article. I’m a little late to the Windows 8 game (I’ve been using OS X exclusively for about 3 years). I just bought a new computer and built it from from components.
I installed my SATA optical drive to the first 6G port and the SSD drive to the second 6G port. I installed Windows 8 with no problems (OEM/System Builder license).
After I spent a little time in W8 (updating drivers and OS software), I decided to add my SATA drives from my previous desktop computer, which had Vista on 1 drive (400GB on 3G INTEL SATA port), and 2 data drives (400GB on 3G INTEL SATA port and 500GB on 6G ASMedia SATA port). I verified the boot device priority in my UEFI settings in this order: 1-Optical, 2-UEFI:Win8, 3-P2:Win8. To my astonishment, Vista booted instead of Windows 8 (no options were ever presented to select Vista or W8).
I couldn’t figure out how to get Windows 8 to boot, so I unplugged the extra SATA drives I had just installed and rebooted. This time, I got the light blue repair windows menu, and no attempt to repair (using the built-in repair options) worked.
I figured I had somehow damaged the W8 system partitions, so with the extra drives removed, I attempt to re-install Windows 8. But the problem is that it still won’t boot up (the installer boots from the DVD, but after initial file copying, it won’t boot the second phase of install). Any suggestions?
I have fixed the “system reserved” problem mentioned above but still have a disk problem. My number 2 disk (SATA 1Tb) is missing in the disk manager. I have tried “diskpart” to recover it using the “add” command but the prompt returns an error message and says the command is not available in this version of Windows (8).
How do I convince the system that there is a disk 2? I have tried changing physical locations and positions on the SATA cable.
I FOUND IT!
I had an old XP program provided by Western Digital to diagnose disk problems. WD found my 1 Tb drive and I ran a test on it. Quick test found no problems; another test “Quick 0′s” failed. I then shut down the system overnight, thinking I had a bad drive and would have to take it back for replacement. However, this morning when I booted up I ran the test again and this time it passed.
I then went to diskmanager and there it was. I formatted it and gave it a drive letter and EUREKA! However, it will be a while until I fully trust it.
Thanks all for the help.