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Windows 7: Converting a dynamic disk to basic without data loss

11 Sep 2011   #1

Windows 7
Converting a dynamic disk to basic without data loss

Hello All,

Would really appreciate some help.

I have a 500GB dynamic hard drive which had a Windows 7 install on it. I wanted to reinstall Windows, so from within Windows setup I formatted the system and Windows partition, leaving a partition containing documents and pictures (i was unable to delete them). From then, Windows seemed unable to recognise the disk so i searched in DISKPART and found that the disk was labelled as INVALID.

After Googling around it looks as though i can simply change the 1C02 in the hex from 42 to 07 - however, my only concern was that the documents i have on this drive are spanned across three adjacent (dynamic?) partitions - so i am concerned that by focing the disk to be basic i will lose the connection between these partitions, if that makes sense?

Sorry if that doesnt make any sense, hopefully these will help explain what i mean (the direct link to the gallery is here:


Acronis Disk Director (see documents spanned)

Active unDelete (again, three partitions)

HxD (showing 42)

So, basically im asking if i am safe to convert 42 to 07 WITHOUT losing any data?

Thank you for any help - i would really appreciate it


My System SpecsSystem Spec
11 Sep 2011   #2

Windows 7 Ultimate SP1 64-Bit

Here is a good tutorial for converting a dynamic disk to basic disk, but you will lose anything you haven't backed up.

Convert a Dynamic Disk to a Basic Disk

There is third-party software on the market, but you have to pay for it.

Convert Dynamic Disk to Basic without Data Loss!
My System SpecsSystem Spec
11 Sep 2011   #3

Microsoft Community Contributor Award Recipient


Backup your DATA.
Take a look at this tutorial:
Convert a Dynamic Disk to a Basic Disk
My System SpecsSystem Spec

11 Sep 2011   #4

Windows 7

Thank you for the reply.

Yes thats the tutorial i read, but i just wanted to confirm that it still applied to my three spanned documents partitions, and not just to one dynamic disk with one partition?

Thank you
My System SpecsSystem Spec
11 Sep 2011   #5

Windows 7x64 Home Premium SP1

This is the type of thing you're talking about
Although the MBR partition table will allow you to set the partition type byte to 3 dynamic and one primary like yours I'm not sure what purpose this was intended to serve as generally the whole disk is basic or dynamic. Most people go dynamic by accident and coverting back is straightforward. Was this deliberate in your case?

Since you are going to reinstall Windows I'd play it safe and
1) Move all your data onto an external Basic HDD with a standard NTFS file system
2) Reformat your 500GB HDD as Basic, NTFS and install Windows
3) then transfer your data back.
My System SpecsSystem Spec
11 Sep 2011   #6

Windows 7

mjf thank you very much for the reply. I would really appreciate your help.

The long story is I did not know the disk was dynamic. I initally had 1 500gb partition containing all my documents and windows files. I created a partition in the free space to copy my documents into so I could overwrite Windows keeping my documents intact. However I did not have enough free space for all my documents so after copying over one batch of files I shrunk the windows partition and extended my document partition. I had to repeat this again so I now have three extended document partitions.

I then put in the windows CD, formatted the OS Recovery, SYSTEM Reserved and Windows parititions but then was unable to install Windows as it did not recognise any disks. I attempted FixMBR etc but to no avail.

So my question is, will changing 42 to 07 preserve the extended partitions. Do I need to repeat for each 42 (like the link you posted) and then the three dynamic extended partitions will then become one basic partition?

At the moment I can not actually see the data so have no idea how to back it up? Otherwise I would do as you say and back it up, format and copy back over.

Any ideas? I would GREATLY appreciate your help

Thank you very much
My System SpecsSystem Spec
12 Sep 2011   #7

Windows 7x64 Home Premium SP1

Quote   Quote: Originally Posted by Bollard View Post
So my question is, will changing 42 to 07 preserve the extended partitions. Do I need to repeat for each 42 (like the link you posted) and then the three dynamic extended partitions will then become one basic partition?
You've carried out a number of operations on this disk and I can only give you my best guess.
If the data wasn't absolutely critical and it was my HDD, I would edit all the (0x42) byte type entries in the partition table to (0x07). I would then expect the partitions to show as Basic primary and if the old file system is in tact then I would expect to see the files. If not I'd take some follow on action. This can be discussed if you go down this route.

I'm more familiar with the screenshots from Windows Diskmanager and Partition Wizard with ALL the status information shown. For example the MBR for Disk 2 shows one partition (status) as active which isn't shown in your status screenshot info. Including full Windows Disk Management screenshots as well would help.
My System SpecsSystem Spec
13 Sep 2011   #8

Windows 7

Thank you for your help and continued support mjf.

I have managed to recovery a few files using R Studio, so will go ahead with the conversion and report back.

Shown below are the screen shots as requested (though they give little information, to me atleast!)

Disk Management (see the invalid disk):

Partition Wizard (not sure how to show all information?):

The album of the two is here: Photo Album - Imgur
My System SpecsSystem Spec
13 Sep 2011   #9

Windows 7x64 Home Premium SP1

thanks for the feedback. If you tried the (0x42) to (0x07) change, some feedback on the outcome would be useful. Was it the screenshots you last posted (& it didn't achieve the desired results?).
My System SpecsSystem Spec
27 Sep 2011   #10

Windows 7


Sorry for the delayed reply.

I attempted the change and some partitions appeared in Windows Explorer (including the old System reserved), however not the Documents partition as i hoped.

I resorted to using R-Studio to "recover" and copy over files in batches.

Moral of the story - always check you have basic partitions!

Thanks for all the help - i really appreciate it
My System SpecsSystem Spec

 Converting a dynamic disk to basic without data loss

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