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  1.    01 Oct 2015 #21
    Join Date : Aug 2015
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    Quote Originally Posted by Joergi View Post
    The help page only says that auto-verify only is available with the full edition of Macrium Reflect. Does the free version of Macrium Reflect offer file verification at all?
    Yes: http://www.macrium.com/reflectfree.aspx

    Quote Originally Posted by Joergi View Post
    Second point: If Macrium Reflect succesfully verified an image file, there is a very high probability that the image file is in good shape. There however still is a (very small, if you ask me) probability that the file verified, although it in fact is not a copy, which is 100% identical. Macrium Reflect cannot prevent that,
    That's precisiely what I meant by no full validation. The further step of confidence I have gotten, when needed for critical imaging, is by actually trying restores on a given system AFTER I've taking a redundant image with other software in which I have confidence, e.g., Image for Windows/DOS/Linux. I would go so far as to term those instances "spot validation" or "validation sampling".

    After all, one full validation (often 3 batches) is all you need in the pharmaceutical industry I work in, at least until you change the process and/or it's equipment.

    P.S. no, I don't test critical restores 3 times because the U.S. FDA doesn't require me to.
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  2.    01 Oct 2015 #22
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    Quote Originally Posted by Word Man View Post

    That page now does not only state that verfication would be included, but also "auto verification" would be in. That contradicts what their other website claimed.

    Quote Originally Posted by Word Man View Post
    That's precisiely what I meant by no full validation.
    Yeah, I guess it's pretty safe to consider a file to be a true copy, if it verified. Chances it is not should be very, very small.
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  3.    01 Oct 2015 #23
    Join Date : Oct 2013
    Covington, Louisiana
    Posts : 735
    Windows 10 1703 Pro 64

    We are talking about two different procedures with Macrium. Clone and Image.
    The OP used the Clone procedure which copies everything from one disc to another. I do not know the procedure for verifying the Clone on Macrium site as I have never used the Clone procedure. The Image procedure makes a compressed copy of the disc or partition and saves it as a file. I have used an Image to transfer my system to a new drive. Macrium uses a hash method for the blocks it copies and has a option to verify the block hashes on the saved Image. In v6 of the free version under Advanced Settings you can select to auto-verify the Image or you can run a manual verify when ever you chose.
    I would suggest to the OP to make an Image with Auto-Verify of his old disk and save it if he ever needs it. He should also make an Image of his new disk.

    Jim
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  4.    01 Oct 2015 #24
    Join Date : Jul 2015
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    10 Pro

    Quote Originally Posted by Word Man View Post
    Yep, only checksum compares for Macrium, not a full validation - http://knowledgebase.macrium.com/dis...res?src=search
    Yeah, MD5 is a 128 bit hash so the chance of 2 files having the same MD5 is only 2 ^ -256.

    That is a small number. Possible but on average only 0.000000000000000000000000000000000000000000000000000000000000000000000000000000000086% of the time.

    That is 76 zeros (hopefully).
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  5.    01 Oct 2015 #25
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    Quote Originally Posted by Phone Man View Post
    We are talking about two different procedures with Macrium. Clone and Image.
    The OP used the Clone procedure which copies everything from one disc to another. I do not know the procedure for verifying the Clone on Macrium site as I have never used the Clone procedure. The Image procedure makes a compressed copy of the disc or partition and saves it as a file. I have used an Image to transfer my system to a new drive. Macrium uses a hash method for the blocks it copies and has a option to verify the block hashes on the saved Image. In v6 of the free version under Advanced Settings you can select to auto-verify the Image or you can run a manual verify when ever you chose.
    I would suggest to the OP to make an Image with Auto-Verify of his old disk and save it if he ever needs it. He should also make an Image of his new disk.
    Cool, thanks for the clarification!
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  6.    01 Oct 2015 #26
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    Quote Originally Posted by Phone Man View Post
    ..I do not know the procedure for verifying the Clone on Macrium site as I have never used the Clone procedure. ...
    Pretty much the same concerning verification - http://knowledgebase.macrium.com/dis...Cloning+a+disk
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  7.    01 Oct 2015 #27
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    Quote Originally Posted by halasz View Post
    Yeah, MD5 is a 128 bit hash so the chance of 2 files having the same MD5 is only 2 ^ -256.
    0.000000000000000000000000000000000000000000000000000000000000000000000000000000000086% of the time.
    That is what I call very, very unlikely.

    Another aspect is the question, which kind of corruption leads to which change in the hash. Harddisks only store ones and zeros. Depending on where inside the file an error happens (a bit is changed), this might have a different effect on the hash. It would then be interesting to know, what exactly would have to be changed in order to create a different file with exactly the same hash.

    MD5 hashes have in the past been used for security ("securely" storing passwords for example). I know there have been scientistists, who have written essays on the probability of being able to create a hash collision:
    Different data, which creates the same hash as the original.
    Usually it does not need one small change in the data, but it needs more or less completely different data in order to get the same hash again.
    The probability that such a huge number of incorrect bits are transferred (with the errors at exactly the right places) is another limiting factor.
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  8.    01 Oct 2015 #28
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    Hoping not to get unacceptably far from the thread topic - I'll just chip in with I think there's a bit more to fully validating image restoration than having a vanishingly small probability that the data was encoded into the image with 100% accuracy. It needs to make a complete round trip across every link in the chain until you're exactly back where you started from. You can only go so far into this before Heisenberg's Uncertainty Principle kicks in.

    Granted, mere "verification" serves me fine from a practical standpoint.
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  9.    01 Oct 2015 #29
    Join Date : Oct 2013
    Covington, Louisiana
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    Windows 10 1703 Pro 64

    Quote Originally Posted by Word Man View Post
    Pretty much the same concerning verification - http://knowledgebase.macrium.com/dis...Cloning+a+disk
    I have read that link but it only mentions doing a Verify File System on the source disk before it starts the clone. No verification on the target disk after the clone.

    Jim
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  10.    01 Oct 2015 #30
    Join Date : Aug 2015
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    Quote Originally Posted by Phone Man View Post
    I have read that link but it only mentions doing a Verify File System on the source disk before it starts the clone. No verification on the target disk after the clone.

    Jim
    Sorry, I rushed that one and they are indeed talking about a different kind of verification there. I didn't find something suitably explicit yet but could go into Macrium when I get home from work and check it out directly.

    EDIT: Right, so yes, I was missing the important distinction between "Auto Verify" per se and "Verify" (more like chkdsk, let's say) in the Macrium context. I imagine in Macrium, cloning and imaging being totally different animals, verify and, in a sense, forensic sector copying, are as far as it goes in assuring an exact clone.
    Last edited by Word Man; 01 Oct 2015 at 17:28.
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