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Different MD5sum after transfer to External Hard Drive

md5 external hard drive large file iso

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#1 Tjcrazy

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Posted 18 June 2012 - 23:19

Hey!

Got a weird problem I'm hoping you guys can help me with.

I've got a large (8.5gb) iso file that I want to transfer from my laptop to my desktop.

I've got a 160gb 7200rpm hard drive, plugged into an external Hard Drive caddy. (So its connected via usb)


I transfer the iso to the external hard drive with no errors on Windows, do a md5 check, and the md5 sum on the external file is always different to the correct original file.

I can't figure out what to do, or why this would be happening!


Any ideas?

(iso files are blurred as they are personal related, no pirating here!)

Attached Images

  • md5.png



#2 primexx

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Posted 19 June 2012 - 05:03

try it on a different media and see if it's the external's fault

#3 Raa

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Posted 19 June 2012 - 05:04

Out of curiosity, the external HDD is in NTFS format?

#4 articuno1au

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Posted 19 June 2012 - 05:12

Is it possible that your MD5 checker is also including meta data (i.e. last change date) information in the MD5 check?

I think that's what Raa was angling at when he asked if it was NTFS.

#5 +BudMan

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Posted 19 June 2012 - 06:07

I think the point about ntfs was more related to fat not supporting over 4GB file size.

You sure its just not your software, trying to make heads or tails out of that screenshot

You got multiple listings? What doesn't match, my guess is your using the software wrong.

How about you just list out the file with the md5 for each?

#6 OP Tjcrazy

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Posted 19 June 2012 - 09:58

NTFS formatted - don't think it would of even worked otherwise!

Interesting about the md5 meta data. Is there a program that checks md5 sums without including meta data?

Otherwise, i'll try another hard drive I have, and see if that works/doesn't work.

The multiple listings are all of the same file. I've tried transferring the iso across to the HD a few times now, and each time its a different md5 result.

#7 AR556

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Posted 19 June 2012 - 10:20

Is the transferred file's md5 always end up the same or is it randomly different each time?

#8 +BudMan

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Posted 19 June 2012 - 12:45

I would try doing some other smaller files to the usb. Try making copies of that file to different location on your disk - does md5 still not match?

Windows copy has built in checks, seems odd that you would have mismatch over something as trivial as 1 file copy. Unless your having issues reading it back from the usb.

Run a chkdsk on the usb drive.

I assume these computers are in the same location - why not just copy the file over the network. I never saw a point to using usb as copy media for devices on the same network. Usb is good if you have to move large amount of data to a different location, backup device, etc. But as a sneaker net for files between computers on the same network - why?

#9 cybertimber2008

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Posted 19 June 2012 - 14:12

Is compression enabled on the drive?

#10 +BudMan

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Posted 19 June 2012 - 15:19

that really shouldn't matter on a md5 check, file would have to be decompressed to check the md5

See copy of file in uncompressed dir, and then same file in compressed folder and same checksums

compressedfilemd5.jpg



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