Recovering ext4 partitions.

How to use TestDisk to recover lost partition
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kbtestdisk
Posts: 1
Joined: 23 Jun 2015, 03:32

Recovering ext4 partitions.

#1 Post by kbtestdisk » 23 Jun 2015, 17:32

Hello All,

I accidently erased my linux disks and like some help.

What happened:
- I wanted to install Windows 10 preview. Being cautious I backed up the mbr on the Crucial CT500MX200SSD1 SSD.

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dd if=/dev/sda of=mbr.bin bs=446 count=1
- Accidently I picked the wrong disk when I did this:

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diskpart -> select disk 1 -> clean
This wiped out the paritions on the disk
- I immediately powered off, and cloned the SSD.
- I wrote the backed up mbr back to the disk, hoping that would restore the paritions. No luck.

What I tried:
I tried testdisk to see if I could restore the paritions. There are atleast 4 paritions on the disk that I know of:
1)ext4: linux root, 2) linux swap 3) linux ext4 (home, and this is the one I am most interested in) and 4) NTFS.
Image

I started with the Intel partition type, which see the 4 paritions but I get the message that the paritions cannot be recovered. Here are two screen shots:
Image
Image


Then I tried the EFI GPT parition type, which again sees the 4 paritions but I get the same message that they cannot be recovered.
Image
Image



Finally I tried the None type, and this sees the 4 paritions correctly. I can even list files and copy from the larger ext4 partition (but this is encrypted so just copying it does not help).

Image
Image

In the image above, I chiefly want to restore the 3rd listed parition (size 640000000) which is the encrypted home parition.


Some other pertinent information:

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> fdisk -l /dev/sdh
Disk /dev/sdh: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/sdh doesn't contain a valid partition table

I'll add the testdisk logs soon.
Thanks for the help in advance.

M.

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Fiona
Posts: 2836
Joined: 18 Feb 2012, 17:19
Location: Ludwigsburg/Stuttgart - Germany

Re: Recovering ext4 partitions.

#2 Post by Fiona » 29 Jun 2015, 06:11

5 partitions are listed but Intel-MBR only supports 4 primary partitions or 3 primaries and 1 extended for logical partitions.
If you choose partition table type None, you cannot write a partition into your partition table, that's why you should choose Intel.
On this screen:
https://lh3.googleusercontent.com/-qcU2 ... /none1.png
There are 5 partitions listed.
The fourth partition overlaps the third partition and can't be recovered.
Should be set to D for deleted.
The fifth partition fits exactly.
Did you have a try to list your files?
Please let me know!
But the fifth partition starts exactly 1 sector after the third one.
That's why I assume, if you try to set it to L for logical, you can receive the message "structure bad".
In case, you should set it as P for primary only.
Your boot partition should be set to star as primary and active.

Currently it's important, can you list your files on your NTFS parttition?

Fiona

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