How to Fix: 'Windows cannot be installed to this disk' Error (RAID)

Dennis Faas's picture

Infopackets Reader Phil P. writes:

" Dear Dennis,

I have installed Windows 10 32 bit and now I am trying to upgrade to Windows 10 64 bit using the clean install method. Since I'm installing Windows 10 from scratch, I am also going to upgrade my C drive performance using 2 x 2TB hard drives (for a total of 4 TB usable data) in RAID 0 configuration. The problem is that when I try to install Windows onto my RAID, it tells me that 'Windows cannot be installed to this disk. This computer's hardware may not support booting to this disk. Ensure that the disk's controller is enabled in the computer's BIOS menu.' I see no place for this selection in the computer's BIOS. Any idea how to fix this problem? "

My response:

This is an excellent question, and there are a few things to discuss here.

For those unaware, RAID stands for "redundant array of inexpensive disks" and is used to combine 2 or more hard drives for various configurations. For example, in a two-drive RAID 0 configuration, data is shared (striped) across both drives. When the computer requests data from the RAID 0, both drives load the data in parallel, which is twice as fast than loading off one drive.

In a RAID 1 configuration, data is mirrored from one drive to the other; if one drive dies, the RAID continues working. In such a case, the user replaces the defective drive, and the RAID automatically rebuilds itself without any interaction from the user.

With that said:

If you intend to boot off of the RAID, you will need a Windows-compatible RAID driver during the Windows installation, otherwise the Windows setup won't see your RAID configuration. Consequently you will see the error message "Windows can't be installed onto this disk" and as you have pointed out, you won't be able to install Windows onto the RAID. Usually you can obtain such a driver from the RAID manufacturer's website.

Even so, any RAID configuration that is greater than 2TB will not be able to boot Windows (when using legacy BIOS) because the hard drive will be configured for GPT (GUID Partition Table) rather than MBR (master boot record) due to size limitations of MBR. Without getting too technical, MBR has been around for a very long time, and GPT is still rather new and not very well supported in Windows.

At any rate: even if you used a RAID 1 configuration, you could still use MBR because both drives would appear only as 2TB instead of 4TB (due to mirroring instead of striping), but you will still likely need a Windows-compatible RAID driver during the Windows setup.

If all of that is confusing to you, please read on because there is a much easier solution noted further down.

Why You Shouldn't Boot from RAID

I don't recommend booting from RAID for a number of reasons.

If you boot from a RAID 0 (and your operating system resides on the RAID 0), then you are at major risk if one drive dies. In this case, the entire RAID goes down and you lose all your data, including your operating system. That's because in a RAID 0 configuration, data is spread (striped) across both drives. If one drive dies, then all the data on the remaining drive is useless.

On a RAID 1 system, data is mirrored on both drives. If one drive dies then the other one keeps going, but that doesn't mean you are free and clear of problems. In this case, if one drive dies or goes out of sync, the RAID will start rebuilding. During this time, all (or in this case, both) hard drives connected to the RAID will be very busy rebuilding data, thus making the operating system extremely slow. It would be so slow, in fact, that the computer will likely be unusable. It's worth noting that RAID rebuilds can take hours or days to complete depending on the setup, so keep this in mind.

In my particular RAID setup, I have 8 x 2TB hard drives in RAID 1E configuration; as far as I recall, it took about 10 days to rebuild one 2 TB hard drive that went out of sync. During that time I could not reboot the system or the entire process would start over.

A Much Better Solution Than Booting from RAID

A much better solution to all of this is to install Windows onto a non-RAID device such as an SSD (solid state hard drive).

Once Windows is installed onto the SSD, you can format your RAID any way you like, and then backup the SSD (and operating system) onto the RAID on a daily basis. That way the operating system remains unaffected if the RAID goes down or needs to rebuild itself. It also makes the primary hard drive (SSD) much easier to reconfigure in case you need to yank it out and put the SSD and RAID into a new system. For the record, an SSD would have the performance of a RAID 0 setup, and most likely even better because SSDs don't have spinning platters (they use chips instead).

This is how I have my own system configured, and based on what I've read from countless books, this is the preferred way of doing things.

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About the author: Dennis Faas is the owner and operator of With over 30 years of computing experience, Dennis' areas of expertise are a broad range and include PC hardware, Microsoft Windows, Linux, network administration, and virtualization. Dennis holds a Bachelors degree in Computer Science (1999) and has authored 6 books on the topics of MS Windows and PC Security. If you like the advice you received on this page, please up-vote / Like this page and share it with friends. For technical support inquiries, Dennis can be reached via Live chat online this site using the Zopim Chat service (currently located at the bottom left of the screen); optionally, you can contact Dennis through the website contact form.

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alan.cameron_4852's picture

A very interesting reply to a problem I am about to encounter.
I have a problem with your suggested solution as it does not ensure that ALL the data on the SSD is protected. It is exposed until the next time the SSD is copied to the RAID. It would mean that the whole system would be inoperable until a replacement SSD is found and installed.

Dennis Faas's picture

There is no way to protect a hard drive and its data 100% of the time, but you can mitigate data loss to a certain extent. For example: if you get hit with a virus / malware that erases the entire hard drive (or encrypts it) then you lose everything even if you're mirroring. That is true even if you're using a 10 disk array.

So, mirroring a 2 disk setup really isn't that great of an idea UNLESS you are worried about the entire system crashing if one drive dies (think of it as insurance) and assuming you're not hit with a nasty virus that nukes everything. In that case, a daily or hourly backup would be a better idea. If you really wanted to, you can easily mirror an SSD by purchasing two and using them to boot Windows (assuming you're using less than 2TB).

jamies's picture

OK - to start with, I'll admit this commentary gets well past the subject of installing windows onto a RAID configuration, but I consider the details to be relevant to anyone considering RAID.
So -
My consideration of RAID starts with asking - for Speed or safety.
There's striping for speed of writing and reading.
5 or more (well certainly more than 3) drives with Parity for speed and recoverability.
BUT - as detailed in the article, repairing a striped setup can be a very slow process. Also assumes that it isn't the motherboard, controller or malware that is the source of the problem - As you'd probably lose all the drives, or all the data on them at least.
Also - whatever RAID controller you are using may not have put the data on the drives in the same way that a replacement controller would do, and expect to find on any set of drives connected to it.
PAIN - as in major problems if you don't have a backup copy of the data.

OK so now look at Mirror RAID - same likelihood of problems if replacing a motherboard or controller, or got malware.

And that also applies to RAID 10 - mirror and stripe combined.

Now, you used to be able to have Windows do RAID mirroring at a partition level via software (as in the drivers), which means that the partitions can be used to maintain a copy of the actual OS and data - but still as vulnerable.

So - if you need speed it's striping and adequate backups -
If it's just security - then You would probably be better off having a pair of removable drives and clone the system to those drives alternately.
That gives you a very recent copy that will actually run your apps, and a slightly older one for dealing with corruption that happened before you took the latest backup.
If you are not going to have the pair of bootable clones, ideally make incremental file level backups of the OS and data partitions so you can recover the partitions and then update those recovered partitions to the latest state.
And - in all cases use a cloud type facility to hold incremental versions of files that are changed.
I say cloud, but what is actually needed is a file level store that cannot be wiped from your PC, or by mains problems in your property - yes UPS and surge protect may be good, but they don't deal with the building being burnt down, flooded, or all the kit being stolen.
And as an organisation I worked for discovered - a fire safe rated safe for 4 hours for magnetic tape media is not a lot of good when the building collapses on the safe and it takes several days for the fire brigade to cool the rubble enough to start looking for the cause.
And my personal experience maybe the PSU, or motherboard, cos the system died while taking a backup -
Goodbye to the OS drive, the data drives and the backup drive - yes I had added to system stress by connecting the extra drive and then doing massively heavy I/O

So - back to cloud - I use Spideroak for my important stuff - incremental copies kept of ALL the files in the specified folders, and they are encrypted in the store (Unlike Windows File History that doesn't encrypt files, and doesn't warn you when it does not take copies of some of the files in the folders, and allows all the PC users to read the files, and/or delete them.)

So -
Mirror for speed of reading
Recovery - 3 clones of the OS and so I can switch in the replacement drives
(And the older copy is offsite.)
And - before Windows 10, a backup was taken before applying fixes or installing new apps/versions/programs.

Image of data partitions and Incremental backups to get back, or view files.
Incremental copies of user files - nice recovery point for files being saved after important data is deleted from them.

So - whatever you do -
Recovery needs to be the primary concern, and from what could happen.
And within that recovery - the time it will take to do it.
After that consider system speed - Hybrid drive, SSD for very frequently used folders - 'attached' as a folder of the main partition.
Just splitting data over 2 physical drives can almost double throughput
Only using the first half of a drive for normal use can help - as managing data on the end half of a drive may be 30% slower
Go for an additional controller - SATA 3 or whatever is currently fastest.
If you have an appropriate add-in and motherboard that may well double throughput.
And - for my systems, a major bottleneck is the cache memory allocated for the MFT - suddenly the most used blocks don't all fit into the cache, so you get thrashing - at 1 time work I was doing renaming files on a large partition was taking longer to do each file than copying a 10Mb file to another drive (and that was USB2 connected).