How to Convert a Dynamic Disk to Basic Disk in Windows 7

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How to Convert a Windows 7 Dynamic Disk to Basic Disk When  Microsoft says It’s Irreversible!

Firstly, Do Not Dance with the Devil!

I made the mistake (again!) of trying dynamic disks with my new Windows 7 installation.  I must have been asleep – the use of this system is seriously frowned upon for most users.  It has several pitfalls not least that it’s high-end Windows specific (i.e not home, basic etc), and it’s impossible to clone partitions for backup or moves, say.

But mainly, it’s supposed to be irreversible AND un-do-able!

Dynamic Disk Option

To convert from basic to dynamic is frighteningly easy (see screen shot).  The reversing option disappears once it’s done and in virtually all Disk Partition Software,  any ‘partitions’, now called volumes, just show as one big monolithic slab of pale yellow disk that has any possible action greyed out!  This was really bad as it was on the system drive…

You’ll see in the screen-shot that there are 3 disks.

Disk 0 & disk 1 were an effort at user-data mirroring originally until I realised what I pile of poo I’d just landed in.  All the initial  recommendations were negative and the prognosis didn’t look good.  See:

• http://www.pcreview.co.uk/forums/thread-1482847.php
• http://support.microsoft.com/default.aspx?scid=kb;en-us;217226&Product=win20 – Cannot Revert Boot Drive from Dynamic Disk to Basic Disk
• http://technet.microsoft.com/en-us/library/cc755238.aspx – Change a Dynamic Disk Back to a Basic Disk

Solution

HxD Screenshot

However, this post gave me a pointer which eventually led to here and the HxD disc editing tool, here.   The Dynamic Disk Converter is a paid for solution and would have worked.  But I tried the Hex Editor approach after a bit more reading around the subject….  WARNING: See my comment on Dynamic Disk Converter here – added 27/7/2010(SP)

The trick, as in Hitch-hiker’s Guide to the Galaxy, is 42!

Specifically, all 42‘s must be converted to 07.

The highlighted area contains the bit to edit and the numbers to edit in this area are those in column 02 that are 42.  So change all the 42’s to 07’s in column 02 in the four highlighted lines.  (n.b. The screendump was taken after I’d fixed the disc, so all the 42s are now 07 and some partitions have been deleted.)

That’s all.

Do NOT twiddle anything else.

Caveat

This post in the thread says to just alter one line – this is wrong!  (There’s a confusing addition at the bottom.  This relates directly to my experience, so yes, all real primary partitions are numbered 07)

And this post says to do them all – this is right.  It shows 3.

In my original pre-editted state, I had 4!  Handily, this shows the reason (I think), why you can only have 4 primary partitions on a drive.

Finale and Actual Actions Summary

Current Disks

Now you’ll see I have only two 07’s in the column (in the screenshot above).  These map to the two partitions showing in my Disk Management full screen-shot here.  For some reason, it had ‘remembered’ other volumes I’d made on the disk – that’s why I had 4 to do.

I was quite prepared to buy the paid-for software.  It looked good and worth the cash.  Instead:

1. I very tediously moved ‘volumes’ into ‘partitions’ onto a third disk I entered into the system.
   1. This later disk needed it’s partitions resizing first to make room.
   2. It was hot-plugged using it’s SATA into the wire from the DVD as I didn’t have any spare SATA wires!  Doh!
2. The moved data was from disk 0 & disk 1, all relevant stuff going to disk 2.
3. Deleted all the volumes from Disk 1
4. I could then set Disk 1 to basic using Windows as per Microsoft instructions.
5. Moved all user data back to C-Drive volume (I had been in the process of separating data from programs).
6. Backed up C-Drive volume and system state using Windows 7 Backup tool to new partition ‘BACKUP’ using all of Disk 1
   1. This was in case the following hex stuff failed.  It would allow an easy restore by:
      1. Install windows from DVD onto Disk 0
      2. Use Windows backup to reset system state and all the files & programs on the C-Drive on Disk 0
7. Now used the Hex editor to edit the disk sector information as described above.
8. REBOOT (fingers crossed!)
9. WAHAY! It worked.
10. Removed pseudo partition remaining on Disk 0 to leave unallocated space  – I think this was due to the invisible 1Mb database that exists on dynamic disks.

Plans

I’ve now got two new hard drives in the post.  When these have arrived and are installed, I’ll use standard tools to move partitions and get user data onto a RAID mirror assembly.  This will increase data integrity and give me a better backup.  You’d think that outboard backups would be fine, wouldn’t you?  Well I bought a Western Digital 1TB Studio Edition which worked okay for a while….

But it ran so hot the eSATA/USB circuitry failed!  I dismantled it and found the drive to be okay – this is the third disk, Disk 2 in the screen-shots!

Now, I have a new system with a better,  heavy-duty power supply, adequate (and quiet cooling), with the whole thing protected behind an APC UPS which I’ve had for a year.  Sticking to basic disks should make backups simpler and the whole thing should be more reliable – certainly more so than the WD Studio thing which is a pile of hot plastic pants.

p.s. added 5/12/2010: read this for my new recommended fast backup solution: http://strangelyperfect.tv/10155/what-is-the-best-backup-for-windows-in-a-small-home-or-office/

p.p.s. added 01/03/2012: I now recommend that folks use the free Easeus software, http://www.partition-tool.com/personal.htm  This will fix dynamic discs using a familiar graphical user interface so is way less scary.  Thanks to those that pointed this out.

p.p.p.s. added 11/11/2014:  I now find AOMEI Partition Assistant Standard Edition works very well and I use it very much.  It has a large feature set for a free utility.

Stick to basic Disks – you know it makes sense!

Further Reading

• http://www.win.tue.nl/~aeb/partitions/partition_types-1.html
• http://www.viralpatel.net/taj/tutorial/partition_table.php
• http://en.wikipedia.org/wiki/GUID_Partition_Table
• http://en.wikipedia.org/wiki/Master_Boot_Record

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