Verifying image - why?

Discussion in 'backup, imaging & disk mgmt' started by sukarof, Sep 18, 2007.

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  1. sukarof

    sukarof Registered Member

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    This is probably a stupid question but what can make a image corrupt when using imaging software?
    I wonder why verifying is necessary? I have never used that feature in the different brands of imaging software I´ve used, the images has always restored just fine. Reading now and then about verifying gone bad I wonder if I have just been lucky or is it not really necessary? Does a failed verified image automatically mean that it can not be restored?
     
  2. Huupi

    Huupi Registered Member

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    Yes i never done it either,my proof is a restore,first restore took some sweating and fingers crossed but thereafter i routinely restore almost unconsciously so to speak,it never failed me.
     
  3. ErikAlbert

    ErikAlbert Registered Member

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    When I had ATI on my computer, I verified all my images.
    With ShadowProtect, I never verified any image, because SP restores my image in 6 minuts.

    My image of "Windows only" restores in 35 seconds, that is my new way of installing Windows from scratch and doesn't require any internet or phone activation anymore. :)

    Karen's Replicator works as fast as ShadowProtect and I use it for backup of my data, the MOST IMPORTANT backup.
     
    Last edited: Sep 18, 2007
  4. Peter2150

    Peter2150 Global Moderator

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    I verify sometimes, but it is as much for test purposes as anything.

    Normally what I would do is mount the image, extract a file, and it's okay, restore it. Restoring is my verification.
     
  5. lucas1985

    lucas1985 Retired Moderator

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    Bad RAM, writing to bad disk sectors, etc, etc :)
     
  6. Huupi

    Huupi Registered Member

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    Good idea to run chkdsk regularly.
     
  7. Peter2150

    Peter2150 Global Moderator

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    After writing this I noticed a post by grnxnm on the storagecraft forum suggesting verify testing images periodically as there are things that can happen. Learn something every day.
     
  8. Peter2150

    Peter2150 Global Moderator

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    I used to do this until I talked to the guys at velocitymicro about this. They recommended not running at all unless there was a serious indication of a problem. Also they said it is the most wear intensive activity you can do.

    What I do now is I have a crash I think might cause a disk problem, rather then running chkdsk, I just restore an image. Heck of a lot quicker.

    Pete
     
  9. Huupi

    Huupi Registered Member

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    Something learned ! thanks.
     
  10. ErikAlbert

    ErikAlbert Registered Member

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    Yes the restore time of my system partition takes 9 minuts :
    1. why would I run "chkdsk c: /f /r" ?
    2. why would I run NOD32, that needs more than 25 minuts to scan my computer ? My restore = 100% removal of all threats. NOD32 can't guarantee that and I do it in 9 minuts or 2 minuts with my boot-to-restore.

    I'm getting closer every day to what I really want.
    The next step is to protect my data partition. :)
     
  11. Osaban

    Osaban Registered Member

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    I still can't see the relationship between verifying with ATI and the restoration speed of ShadowProtect. A fast restoration means a successful one? Maybe I'm missing something.
     
  12. nexstar

    nexstar Registered Member

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    Also, and maybe I'm missing something here as well but, if the purpose is to check the integrity of the backup and the backup has now replaced what was backed up, then what if the backup actually proves to be corrupt? :eek:

    Graham
     
  13. ErikAlbert

    ErikAlbert Registered Member

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    When I had ATI, I always used the Linux CD. Restore-time = 30 minuts.
    That's not practical, to restore an image as verification. That's why I verified my images.

    With ShadowProtect I restore also with my Recovery CD. Restore-time = 6 minuts.
    That IS practical to restore an image as verification.
    Load-time of CD = 3m + Backup = 4m + Restore = 6m Total time = 13 minuts.
    That is fast enough for me and I know for sure that my image can be restored, because I tested it.

    Is that an answer to your question ? :D
     
    Last edited: Sep 20, 2007
  14. Huupi

    Huupi Registered Member

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    In general a verify of an image gives you some prediction about the health of that image,if it verify with no errors is not always a guarantee that it wil restore sucsesfully,just as on the Acronis forums there are many who complain about verifying with no errors but can't restore.So the only reliable mean is to restore an image.For the first time restore its saver to restore to a second drive,if it works out then you can restore to the original and hope that your diskcontrollers and other stuff are supported,but then as Nate said filecorruption and diskrot can happen over time,so there is no 100 % guarantee.From what i read here on Wilders about SP there are almost no complaints about the essentials of this app.Trivial things like not correct timestamp etc.are for me as an enduser just cosmetical issues.
     
  15. ErikAlbert

    ErikAlbert Registered Member

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    I always mention the date and time in the backup file name, especially when I work with the Recovery CD. Something like this :
    "SYSTEM 20070920 1712", which keeps my backup files properly sorted. Last file = last backup.
     
  16. Huupi

    Huupi Registered Member

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    Windows itself create a timestamp on any data created so also with an image,its placed just behind the filename.[choose details from the popup in image].
     
  17. ErikAlbert

    ErikAlbert Registered Member

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    I know, but that doesn't improve anything. That timestamp should be on the first screen.
    We have a rule at work : "Always show the REQUIRED data on the screen, that the user needs, to do the job properly."
     
  18. Huupi

    Huupi Registered Member

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    If you tick details in the popup then it will always be there at first sight,its that easy.I dont know what your problem is !?!
     
  19. nexstar

    nexstar Registered Member

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    Yes, I fully agree. I had several problems in the past with ATI verifying images as ok but then saying they were corrupt when I came to restore them :( . Although I'm not sure if that is a failing of verification generally or of ATI's implementation of it at that time.
    This shouldn't be the case if the verification is done correctly.
    Yes, if the image restore is to a second drive and that is booted from to test it then there is no risk at all. I suspect though that most don't do it that way.

    I would personally prefer to use a verification routine which is non-destructive to the original source of data. From a safety point of view, if the new image is being written straight back to the drive it came from then it would be better not to restore it at all unless, and until, it was really needed and to just assume that it is ok. That way, you have the data which you know is ok and an image of it which is probably ok. The other way, you end up with a single restored image which is probably ok.

    That's just my view and everybody's entitled to approach it differently :) .

    As to the OP's question, in the last 2-3years I have never had a verification fail so it could be argued "what's the point?". I think it was much more important when hard drives were more likely to fail and the burning of cd/dvd's could be unreliable. If the data is important to keep then, for the short time it takes, I'll verify the image. If I'm just testing stuff out then I don't bother.

    Graham
     
  20. Osaban

    Osaban Registered Member

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    Yes, it answers my question in the sense that Sukarof was using the term 'verifying' as 'validating', and you use the term verifying as trying out your image (on the grounds that it takes only a short time).

    The point is if your image made from ShadowProtect is corrupted, whether you image in 6 minutes or 30 it will remain corrupted. Sukarof is right in asking if one can restore from an image that has been validated as corrupted.

    When I backup with ATI there's an option to skip errors when backing up, which I have never considered, but I'm also wondering if the existence of errors in the backup would eventually hamper a restoration.
     
  21. Peter2150

    Peter2150 Global Moderator

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    No way I would consider restoring or saving an image that verified as corrupted. Just doesn't make sense. Only time I had a bad image with SP was when I was testing an unreleased version. It verified bad, so I didn't try to restore. Turned out to be a bug in the verify routine. Point is why try a restore if you at all suspect the image.
     
  22. sukarof

    sukarof Registered Member

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    I just wondered because the verification process relatively often seems to fail when reading forums, so I wonder if verification process really is reliable. My approach has always been that if the imaging doesnt produce any error messages then the images are good to restore, and they have been so for me always, but as I said it might just me being lucky.
     
  23. Peter2150

    Peter2150 Global Moderator

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    Well I feel that way with Shadowprotect, based on all the restores I've done. I am just a bit more thorough with the testing, as I've self induced some of the reasons for imaging, so it's kind of nice to know the image is good. They always have been.
     
  24. EASTER

    EASTER Registered Member

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    I used to experience verification failures with TI but that was a long time ago. Since then, and with Paragon Drive BackUp + DriveSnapshot i've yet to realize any failures, not only thru program verification but also with the restores.
    I believe the latest imaging technology is made great strides against such failures but they can and do still occur for users. I honestly believe that the failures i experienced were due to lack of adequate memory/resources now that XP and Vista is here. My probs were experienced only on 98, and thats been a great while back.

    Certain power/program interruptions i understand can lead to image corruption but aside from that, most if not all Imaging Programs SHOULD deliver a fine quality image ready to restore completely and without issue.

    I won't comment on TI since i don't use it except that i do have it for my Seagate drives courtesy Seagate Drive Wizard app.
     
  25. Osaban

    Osaban Registered Member

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    I've been backingup with ATI every week for the last 6 months, and validation whether within Windows or with the recovery CD has always shown positive results. Likewise I've restored an image 3-4 times because of real problems and it went well.

    Every other month I transfer the backup to DVD using Nero as a precaution against my USB drive failing, and out of 4 DVDs created by Nero there is always 1-2 which show errors. Making a second copy usually rectifies the errors(it sort of shows that the transfer of data itself might get altered in the process).

    I definitely think that veryfying/validating is worth doing everytime, even though it is time consuming.
     
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