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Windows 7: Best way to sort out a corrupted partition table?

19 Nov 2014   #1
firehorseuk

Windows 7 64bit
 
 
Best way to sort out a corrupted partition table?

Hi,

My Hitachi Touro 4TB disk partition got corrupted.
Originally it was one 4TB partition with about 2.5TB of files.

One minute it was fine, then it came up with "Need to format hard disk before use", then it wouldn't even start up.

The disk is currently mounted in a disk dock. The disk wouldn't start up in its original enclosure so there might have been a hardware problem with the electronics of the enclosure which corrupted the drive.

Now it has 3 partitions

465.75 GB RAW - Healthy (Primary Partition)
1582.25 GB Unallocated
1678.02 GB Unallocated.

I have tried TestDisk but for some reason after about an hour of scanning or so, the drive seems to switch off. But it seems fine when I'm using Windows software. I've tried writing MBR but TestDisk says it can't!!

Should I use something like easus partition manager and set the primary partition back to one 4TB partition and then use recovery software to recover the files or is there a better way?

Thanks


My System SpecsSystem Spec
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22 Nov 2014   #2
Mark Phelps

Win7 Pro 32-bit, Win8 Pro 32-bit
 
 

Sorry to say this, but in every instance where any of my partitions were reported as "raw", that mean that the drive had suffered physical damage. And, in NONE of those cases was I able to recover anything of any of the drives.

I had two fairly new Seagate drives do this to me last year, and in both cases, they were sudden head crashes.
My System SpecsSystem Spec
23 Nov 2014   #3
firehorseuk

Windows 7 64bit
 
 

Hi Mark,

Quote   Quote: Originally Posted by Mark Phelps View Post
Sorry to say this, but in every instance where any of my partitions were reported as "raw", that mean that the drive had suffered physical damage. And, in NONE of those cases was I able to recover anything of any of the drives.

I had two fairly new Seagate drives do this to me last year, and in both cases, they were sudden head crashes.
Eek, sorry to hear about that.

Hmm .. head crash could mean the heads were damaged beyond able to read anything

Can I ask which software did you use?

I'm trying Zero Assumption Recovery at the moment but its going to take a while to work its way through everything.

I've gone into the Windows 7 power management and in advanced settings, changed hard disk/turn off hard disk after from 20 to 999999 minutes. After ZAR has finished, I will have another go with TestDisk to see if those settings will keep the hard disk online for TestDisk to do everything.
My System SpecsSystem Spec
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23 Nov 2014   #4
Anshad Edavana

Windows 7 Ultimate x64
 
 

Hi

I don't think neither your HDD is faulty nor your data are lost.

Quote:
The disk is currently mounted in a disk dock. The disk wouldn't start up in its original enclosure so there might have been a hardware problem with the electronics of the enclosure which corrupted the drive.

The fact that your disk won't even recognized if connected to the original enclosure but will be recognized when connected via dock clearly means the enclosure is faulty.Then you may ask what happened to your original partition.

You may know that a hard drive's storage area is divided in to smaller chunks known as "Sectors". Historically a sector is 512 bytes in size. With MBR partitioning scheme, the maximum size of a partition you can create with a 512 byte sector sized disk is 2TB. This was not a problem for decades because hard drives are typically only a few 100 gigabytes in size. When large capacity drives like 3TB and 4TB are introduced, the 2 TB barrier became a real issue. To circumvent the 2 TB limitation, disk manufacturers used USB-SATA bridges which will store data in 4096 bytes chunks instead of old 512 bytes chunks. If you connect such a disk directly to a SATA port, you will expose it's native 512 byte sized sectors and the system won't recognize any data inside it ( while your data is intact safe on the disk ).

The disk management screenshot you posted shows a single 465.75 GB partition. This is with 512 bytes addressing. If you connect this same disk to the enclosure, 4096 bytes addressing will be used. Since 4096 is 8 times higher than 512, simply multiply the partition size with 8 to get it's original size.

465.75 x 8 = 3726


So your original 3726 GB partition is still there and Windows will hopefully recognize it if you connect the disk to a compatible enclosure ( same model is preferred ).

reference : http://www.wdc.com/wdproducts/librar...579-771501.pdf
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23 Nov 2014   #5
firehorseuk

Windows 7 64bit
 
 

Hi Anshad,
Quote   Quote: Originally Posted by Anshad Edavana View Post
The disk management screenshot you posted shows a single 465.75 GB partition. This is with 512 bytes addressing. If you connect this same disk to the enclosure, 4096 bytes addressing will be used. Since 4096 is 8 times higher than 512, simply multiply the partition size with 8 to get it's original size.

465.75 x 8 = 3726


So your original 3726 GB partition is still there and Windows will hopefully recognize it if you connect the disk to a compatible enclosure ( same model is preferred ).
I like your explanation of how it became 465.75GB.

The original enclosure is the something like this
Hitachi 0S03400 - Touro Desk 4TB USB3.0 3.5'' External Hard Drive - Black: Amazon.co.uk: Computers & Accessories

It is fully enclosed never intended to be opened. I had to find a youtube video explaining how to break one of these apart to get at the disk!

So ... does anyone know of any software that can go from 512byte sector addressing back to 4096 addressing to get back at the original data.

More information as I start digging around in this subject. I used HD Sentinal and it comes back with 1995 bad sectors I guess I should have been using something like that to warn me it was going to fail!
My System SpecsSystem Spec
23 Nov 2014   #6
Anshad Edavana

Windows 7 Ultimate x64
 
 

Quote:
I used HD Sentinal and it comes back with 1995 bad sectors I guess I should have been using something like that to warn me it was going to fail!
Hitachi has it's own tool to test drives called "WinDFT". You can download the program and run a test to verify the drive's health status. Make sure to read the user guide before running the tool.

Downloads | HGST Storage


A 4 TB disk will have millions of sectors. Even if there is 1995 bad sectors, chances are great that 95% of your data will be intact.

You can buy a standard USB enclosure which supports 4 TB. Like this one - USB 3.0 External Hard Drive Enclosure | For 3.5in SATA HDDs | StarTech.com

I am not exactly sure whether a generic USB enclosure will work with your drive but probably it will ( otherwise the disk will be detected as "not initialized").

While searching for a USB case, i found these ;

Multiple 4TB Sata drives moved from USB enclosure all have RAW & Unpartitioned space - AnandTech Forums

4TB drives moved from USB enclosure have RAW & Unpartitioned space? - Hard Drives - Storage

The user "fzabkar" is a real "guru" in data recovery ( He posts at several DR forums where i am also a member). You can send him a PM for advise.
My System SpecsSystem Spec
23 Nov 2014   #7
firehorseuk

Windows 7 64bit
 
 

Hi Anshad,
Quote   Quote: Originally Posted by Anshad Edavana View Post
Hitachi has it's own tool to test drives called "WinDFT". You can download the program and run a test to verify the drive's health status. Make sure to read the user guide before running the tool.

I am not exactly sure whether a generic USB enclosure will work with your drive but probably it will ( otherwise the disk will be detected as "not initialized").
Thanks for your advice.

I downloaded Hitachi's WinDFT. It didn't find the drive.

Based on the thread you sent me to, it makes a lot of sense.

Drive has 4096 sectors via Hitachi USB-SATA bridge but when connected directly to Windows, Windows uses 512 sectors.

I tried plugging it back into the Hitachi case, but it doesn't even come up in Windows.

I have a case - Akasa Integral P2STON case

I plugged the drive in - usb drivers installed but then it came up with the message

"The detected capacity (1678 GB) of the drive Disk: #6: Hitachi HDS724040ALE640 [PK1311PAG0VKSJ] is not correct, the capacity should be 3726 GB.

Using the drive may cause file system corruption and/or data loss. It is recommended to check and modify the configuration or upgrade the operating system, hard disk controller and/or drivers to safely use this device."

and then

"You need to format the disk in drive K: before you can use it."

In Administration, it comes up as 465.75GB.

So ... before buying another enclosure, I need to hunt for some software that will read a hard with 4096 sectors via the SATA interface. I don't suppose you know any ?
My System SpecsSystem Spec
23 Nov 2014   #8
firehorseuk

Windows 7 64bit
 
 

Ha,

I'm making progress.

I tried mounting the drive in an Akasa enclosure but that came back with 1.67TB under Testdisk, so I put it back into my Startech disk dock and "Phew!", it came back with 4TB disk.

Under Testdisk, when I was looking at "Geometry", I realised that it a default 512 byte sectors. Now I understand a little bit about sector sizes, I changed it to 4096 sectors and when Testdisk analyzed the disk, it came back "green" :-)

So now I'm going to use the copy function and pull those files off.
My System SpecsSystem Spec
23 Nov 2014   #9
Anshad Edavana

Windows 7 Ultimate x64
 
 

Quote:

Under Testdisk, when I was looking at "Geometry", I realised that it a default 512 byte sectors. Now I understand a little bit about sector sizes, I changed it to 4096 sectors and when Testdisk analyzed the disk, it came back "green" :-)

Good to hear that. Although i uses "TestDisk" a lot, i never played with disk geometry - i never had to dealt with a 4 TB disk before. I hope you will get all your data back safely .
My System SpecsSystem Spec
02 Dec 2014   #10
firehorseuk

Windows 7 64bit
 
 

OK,

Testdisk isn't only good for reading 4096 byte sectors, it is also great for data recovery.

Data recovery was a bit tedious as the drive kept disconnecting at random intervals. Something 20 mins, sometimes 20 hours. But I just kept going from the last time it stopped.

At first I thought the Testdisk had got stuck because it would pull off a whole load of files and then kind of stop. The recovered file size would slowly, slowly increase. I kept restarted Testdisk and moved onto the following files.

I then went back to all the files that Testdisk had a problem with, left Testdisk running on them ... and it eventually read the data and recovered the file. So the only thing I can think of is that Testdisk just kept trying different algorithms to read the data off the disk or it just kept trying.

So fantastic. All data recovered.

Awesome program.
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