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Windows 7: Unallocated drive, partition recovered but not recognized

10 Dec 2014   #21

Windows 7 Home Premium 32 bit

Yes, why PW is refusing to assign a drive letter and make it visible in Windows is still a mystery.

When you have finished copying the partition to another drive and satisfied that you have all data and breath easy :), we shall try and see whether that 3TB external drive can be recovered as it is.

You would initialise the drive after backing up some important sectors with Bootice .

The common and mistaken perception is that initialisation will destroy all data. I very often see even learned Gurus saying " No, No do not initialise. You will be doomed and lose all your data"

Wrong. Initialisation only prepares the drive and makes it visible to Windows Disk Management, ready for creating volumes and then formatting. - that is your drive from being "Unknown" and "Unallocated" will be brought "online" but still "Unallocated"(in the case of a fully wiped out drive being initialised as a GPT drive.) It does not write anything to Sector 264192 or thereafter where the first partition begins and data exists (if already existing)

In the case of a GPT drive initialising writes the Protective MBR to LBA (sector) 0, GPT Header to LBA 1,and part of the Partition table,the 128MB MSR, to LBA2 and nothing more.

(The first volume when created will be at LBA 264192 - you can see it in the PRW screenshot in your first post. (34 is the start of 128MB MSR))

The following screenshot is my 750GB external HDD initialised as GPT - just initialised, I haven't created any volume yet.

Unallocated drive, partition recovered but not recognized-11-12-2014-09-47-50.jpg

So let us know when you have backed up all data in the drive and then we shall backup the relevant sectors as it exists now - just for safety so that we can restore back should we need it - and then let Windows to initialise the drive.

I have to runout now.

My System SpecsSystem Spec
11 Dec 2014   #22

Microsoft Community Contributor Award Recipient

Microsoft Windows 7 Home Premium 64-bits 7601 Multiprocessor Free Service Pack 1

Is the partition still visiable in PW if you DON'T scan for it?
My System SpecsSystem Spec
11 Dec 2014   #23

Win 7 Ultimate x64

Jumanji, thanks for your explanation about how initializing a GPT partition works. It's good to know that initializing the disk won't destroy the data!

Kaktussoft, yes, the partition I'm trying to recover is visible in PW even when I haven't yet scanned for it. It just won't hold a drive letter and Windows won't see it.

Overnight, I copied the partition to another drive. All of the data appears to be there, and the files open and perform normally. In short, the data is now safely backed up.

I will download Bootice and take the drive back to work with me, so we can see if it's possible to get Windows to recognize the damaged partition.

Again, many thanks for all of your help so far!

My System SpecsSystem Spec

11 Dec 2014   #24

Windows 7 Home Premium 32 bit

When you download Bootice you may have to download the 64bit version or 32bit version according your Windows 7 OS.

More programs by iPauly - Softpedia ( I used to download it directly from iPauly's site but now its all in Chinese .)

Saving with Bootice: Lost partitions!

Save the sectors shown when you click on the Partition button. Give an identifiable name to each saved sector.

There is absolutely no hurry. Do it leisurely. ( I am also a little busy this and next week and may disappear from here frequently, peeping in once in a while.)

Before I run out again, I wanted to post this. So I booted again and hurriedly typing this: If you proceed with asking Windows Disk Management to initialise as GPT, stop with initialisation. Do not proceed further to create a New Simple Volume, assign a drive letter and format it.If need be, we shall do it later.
My System SpecsSystem Spec
11 Dec 2014   #25

Windows 7 Home Premium 32 bit

Before I retire for the day I shall leave further steps to be processed.

In case mere initialisation, does not bring back your 3TB external drive alive:

1. In Windows Disk Management , select your 3TB external drive's unallocated/unformatted/Raw portion, create a New simple volume for the full extent of that space and proceed to give it a drive letter.In the next screen you will be asked to format.Select no format option and finish.

(In case the initialisation process rewrites the partition table for only the 128MB MSR partition and at the sametime deletes the single volume partition table (for the partition starting at LBA 264192 which was earlier written by PW scan at LBA 2), this process will rewrite the partition table for that volume. In addition you have also assigned a drive letter to that drive)

This in all probability should bring your drive back alive.

Caution: In all these steps, make sure that you are performing all operations on your 3 TB external drive and not on your system drive or any other external drive. In fact plug out all other external drives.

If this experiment succeeds we will truly have a unique way of dealing with this problem.

Thank you for cooperating with this experiment.
My System SpecsSystem Spec
11 Dec 2014   #26

Win 7 Ultimate x64

Thanks Jumanji

It looks like it will take me some time to backup the sector information using Bootice. I'll work on that when I get a chance during the day. And yes, I will be quite careful not to initialize my boot drive or any other healthy drives!

Many thanks again for your help,

My System SpecsSystem Spec
11 Dec 2014   #27

Win 7 Ultimate x64

Jumanji, I have backed up the sectors as you specified in your linked post using Bootice. When I have time tomorrow, I will go ahead and try to initialize the drive but not format and see if that fixes it. Thanks again, April
My System SpecsSystem Spec
12 Dec 2014   #28

Win 7 Ultimate x64


I have followed your instructions and initialized the disk as GPT. I could not access the partition. So I went on to create a new simple volume and assigned drive letter U:, "Do not format this volume".

The drive is now visible in Windows, but I can't access the contents. Each time try to explore the drive I get the message "You need to format the disk in drive U: before you can use it". Unfortunately, it looks like this fix won't work in my case :-(

At this point, since my data has been safely backed up, I'm going to go ahead and format the drive then put the data back where it was.

I am very, very grateful to you and Kaktussoft for your time and help. Without the guidance in your many posts, I would not have recovered my files!

Many thanks, be well,

My System SpecsSystem Spec
12 Dec 2014   #29

Windows 7 Home Premium 32 bit

Thank you for trying out my suggestions.May be there is still something "unknown" just as we don't know why even after PW recovered the partition, Windows wouldn't take a drive letter and make it visible.

I have to salute Kaktussoft for his wonderful suggestion of "Copy Partition" that enabled you to recover all the data. It never occurred to me and left to myself I would have gone ahead with TestDisk to retrieve the data.

You may go ahead and format your drive abinitio after giving it a full wipe.

And also have a backup always. That will make us redundant and you will be your own Guru.:)
My System SpecsSystem Spec
12 Dec 2014   #30

Win 7 Ultimate x64

Thanks again Jumanji. Truly, all of my drives as large as 2Tb get backed up weekly, and my operating systems drives get backed up daily or every two days. For my 10 3Tb drives I have purchased a software RAID parity solution, but haven't gotten it configured properly yet. This has been a good reminder that I need to make that a priority! April
My System SpecsSystem Spec

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