USB stick unreadable Topic is solved

Using TestDisk to repair the filesystem
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Lansdowne
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Joined: 06 May 2012, 21:25

USB stick unreadable

#1 Postby Lansdowne » 06 May 2012, 21:53

I have a 8GB memory stick, pen drive, whatever, which can not be read.
Under Linux I have tried to read the sectors by both the following
od -Ax -tx1 /dev/sdc >hexdump.txt to give a text file with the first 1M bytes in readable hex
dd if=/dev/sdc of=dump.bin to make an exact copy of the first few MB.

Both show the same 512 bytes repeated throughout the "disk". My guess is the hardware is not reading the actual contents of the disk. If so, I assume TestDisk will not be able to recover the contents?

thanks for any advice.

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Fiona
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Re: USB stick unreadable

#2 Postby Fiona » 07 May 2012, 15:41

Would it be possible to upload a screen from TestDisk / Analyse?
It's your current partition table.
If your partition table is ok, it might be possible to have a boot sector diagnose.

Fiona

Lansdowne
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Joined: 06 May 2012, 21:25

Re: USB stick unreadable

#3 Postby Lansdowne » 08 May 2012, 20:09

Well the Analyze returns "Partition sector doesn't have the end mark 0xAA55"

Quick Search produces no entries in the table.

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Fiona
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Re: USB stick unreadable

#4 Postby Fiona » 11 May 2012, 06:38

Well the Analyze returns "Partition sector doesn't have the end mark 0xAA55"

It only means that the boot sector is damaged or there is no boot sector.
Did you find any partition?
Also what is displayed at Disk in Analyse?
Sometimes I'm using partition table type None to have a boot sector diagnose.
Bit it's a different case.
It's for me difficult to suggest/diagnose something if I don't get any info.

Fiona

Lansdowne
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Joined: 06 May 2012, 21:25

Re: USB stick unreadable

#5 Postby Lansdowne » 11 May 2012, 22:44

Hi Fiona, thanks for the reply.
As I said Analyze displays the message about 0xAA55. That is having selected FAT. If I select partition type None, Analyze gives a 'partition' as follows:
P Unknown from 0 0 1 to 1022 97 38.

Again quick search, and also deeper search, give an empty partition table.

Of course i would not expect anything else, as the disk is reporting the same contents for every sector as I said. I wondered if you had any experience of this situation to suggest something might be recovered ?

thanks again

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Fiona
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Re: USB stick unreadable

#6 Postby Fiona » 12 May 2012, 08:10

Most thumb drives are not Intel Standard.
But I can't judge it, because I didn't get any info how your thumb drive is listed as "Disk" in testdisk.
Also what is displayed at Disk in Analyse?

It's from my previous post!
I've still have an idea to diagnose the boot sector of your thumb drive.
If I select partition type None

Just keep this as None.
But don't confirm at Analyse but Advanced.
Check Type and press enter.
Check your previous file system (I've no idea either, has it been FAT32 or NTFS?).
Normally thumb drives are preformatted using FAT32.
So I assume FAT32?
Check FAT32 and press enter to continue.
Check Boot and press enter.
Check rebuild BS and press enter.
If it was succsesful you see a menu List.
Check it and press enter.
Do you see your data or an error message?

Fiona

Lansdowne
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Re: USB stick unreadable

#7 Postby Lansdowne » 12 May 2012, 16:22

The message was : Can't find cluster size.

But I don't really understand why you are suggesting all these steps which read and analyze the disk. We know that any instruction to read any sector/cluster/whatever will produce the same nonsense (as per my first post). What I do not know is whether there is hope by writing something to the disk (for example trying to re-create a boot sector) that the hardware will behave differently. Maybe you have no experience of this type of problem.

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Fiona
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Re: USB stick unreadable

#8 Postby Fiona » 13 May 2012, 13:10

I asked a couple of times to get infos how your disk is listed.
But you didn't give any info.
So I have no idea, does you start and size of your thumb drive and your LBA fit?
What I do not know is whether there is hope by writing something to the disk (for example trying to re-create a boot sector) that the hardware will behave differently. Maybe you have no experience of this type of problem.

Sry, after loss of data, I'll never suggest or write to a disk, that the disk will behave differently.
This has nothing to do with datarecovery but increasing damage.
Before you go to change anything, you must have a partition.
If you have no partition you will have no boot sector either.
Just an empty and not accessible stick.
Only refusing infos doesn't help as much.
Would be an idea;
If you have valuable data see a professional.
If not:
Checking your hardware, diagnose it using S.M.A.R.T. would be in any case the first.
If you experience read errors and no sectors are readable then it looks like yout pen drive is defective.
Just as long as your thumb drive is recognized correctly and the size also, you can have a try to recover data.
But in your case to have a try to access partition table didn't cause any read error but a message that there is no partition or an invalid boot sector.
Until yet I didn't get any piece of info about that.
Using partition table type Intel aligns created partitions on cylinder boundary.
Using partition table type none doesn't align anything.
So in both cases, the start and size is different.
Only if you catch the right partition you would be able to get your partion and data using TestDisk back.
That's why I made this effort.
But I didn't use Analyse and Quick Search etc.. until yet, because I tried to diagnose a boot sector.
As you can see both is different.
Intel didn't display any partition so there is no boot sector diagnose possible.
None displayed an Unknown partition where you added the partition type FAT32 and a boot sector diagnose was possible.

If partition recovery is not successful, then you can try datarecovery software.

But it looks like that you know the ropes better then I do!
Sry I can't help in your case.
Not to get any infos but suggestions didn't help as much either

Fiona

Bicgatepc02
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Re: USB stick unreadable

#9 Postby Bicgatepc02 » 22 Jan 2013, 06:30

As you say, it really has taken the pressure off knowing she has found the copies of her files. Just wish she'd found them sooner.:-D









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bwendo
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Re: USB stick unreadable

#10 Postby bwendo » 04 Sep 2013, 08:15

I am getting the same error as Lansdowne and following the prompts from Fiona it has helped me get through this - my first time on testdisk and although I am new to it it has worked for me so thanks everyone - great resource and great tips.
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