Touch Checksum mismatch on Read-back from uSD

swamp thing · 11-29-2013, 07:03 PM

[1]Used Win32-Imager to make an image of the internal SD card
[2] Copied the image into a new card
[3] Immediately read back from new card into another image file.
[4] Compared the MD5 checksums of the two images -- they do not match.

Is this normal? ... Or, it corrupted data waiting to brick my Kobo whenever it hits the bad part? [Note that the new card does work on the device, only much slower].

Thanks,
Swamp Thing

GeoffR · 11-29-2013, 10:33 PM

If the imaging program is creating a raw image, and the cards are the same size, then the image you read back should be byte-for-byte identical to the image you wrote so the checksums should match.

I haven't used win32-imager, but if it is this program http://sourceforge.net/projects/win32diskimager/ then it says it creates raw images.

swamp thing · 11-29-2013, 11:03 PM

Quote:

Originally Posted by GeoffR

... but if it is this program http://sourceforge.net/projects/win32diskimager/ then it says it creates raw images.

Yes, that's the one I used.

giorgio130 · 11-30-2013, 04:32 AM

Well, often cards differ in the exact number of sectors, this could be the cause. If it works, I wouldn't worry too much.

swamp thing · 12-01-2013, 08:46 AM

Thanks, giorgio130.

I checked the disk sizes and yes, they were a bit different.

11-29-2013, 07:03 PM	#1
swamp thing Enthusiast Posts: 38 Karma: 10 Join Date: Nov 2013 Device: Kobo Touch	Checksum mismatch on Read-back from uSD [1]Used Win32-Imager to make an image of the internal SD card [2] Copied the image into a new card [3] Immediately read back from new card into another image file. [4] Compared the MD5 checksums of the two images -- they do not match. Is this normal? ... Or, it corrupted data waiting to brick my Kobo whenever it hits the bad part? [Note that the new card does work on the device, only much slower]. Thanks, Swamp Thing

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11-29-2013, 10:33 PM	#2
GeoffR Wizard Posts: 3,821 Karma: 19162882 Join Date: Nov 2012 Location: Te Riu-a-Māui Device: Kobo Glo	If the imaging program is creating a raw image, and the cards are the same size, then the image you read back should be byte-for-byte identical to the image you wrote so the checksums should match. I haven't used win32-imager, but if it is this program http://sourceforge.net/projects/win32diskimager/ then it says it creates raw images.

11-30-2013, 04:32 AM	#4
giorgio130 Time Waster Posts: 422 Karma: 289160 Join Date: May 2011 Device: Kobo Glo and Aura HD	Well, often cards differ in the exact number of sectors, this could be the cause. If it works, I wouldn't worry too much.

12-01-2013, 08:46 AM	#5
swamp thing Enthusiast Posts: 38 Karma: 10 Join Date: Nov 2013 Device: Kobo Touch	Thanks, giorgio130. I checked the disk sizes and yes, they were a bit different.