Exactly how do you restore from Differential or Incremental images? B&R 12 Home!

Discussion in 'Paragon Drive Backup Product Line' started by ratchet, Dec 9, 2012.

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  1. ratchet

    ratchet Registered Member

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    I'm assuming the methods are similar. What I've been doing is just doing basic images to my external HD, which happens to be a SSD. After three images (three weeks) I delete them and start over again.
    Let's say I imaged the 1st of the month then a Diff or Incr on the 8th, again on the 15th and finally on the 22nd. Now something happens on the 23rd and I want to restore the PC to the way it was on the 22nd. Do I select the base archive plus the 22nd Diff or Incr? If so, is there a prompt to do so? Or, do you just select the date of a Diff or Incr?
    Lastly, which method consumes the most space over time on a HD, the differentials or incrementals?
    Thank you!
     
  2. seekforever

    seekforever Registered Member

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    Take this FWIW since I don't do differentials or incrementals, only Full.

    The normal way for a program to behave is to just select the differential from the date you want and it will then restore the system to that date and the only way it can do that is to also restore the base. This implies there is no need to restore the base then the differential.

    Both a differential and an incremental are based on a previously created "full" image. This is very obvious in the case of the differential which always is based solely upon the full base image. The first incremental that is made is based on the full (so in that particular case it is the same as a differential) but after that it is based on the full and all incrementals up to the time the new incremental is being made.

    So if you had a full and then added 1MB of new files each day for 5 days the incremental size total would be:
    Full +1,+1,+1,+1,+1=Full +5MB
    The differential would be:
    Full +1,+2,+3,+4.+5 = Full+15MB
    It takes more because the latest differential has to include all the changes from the base not the last differential as in the case of the incremental.
    This is a simplistic example but it shows the idea.

    Normally if you are doing differentials you can avoid keeping any previous ones since the last one has all the changes since the Full. However, you lose the rollback capability except rolling back to the Full. Note that if you throw the intermediate ones away in our simplistic example the differential and incrementals are the same size (Full +5MB).

    In creating and restoring the archives, creating incrementals is faster because it only needs to write out the very last changes whereas the differential has to re-write all the changes. On restoring the differential is usually faster. Given that we usually create far more archives than we restore then the speed advantage probably lies with the incremental.

    A caution if you feel the urge to make long chains of incrementals. If any incremental in the chain is bad then all the others created after the bad incremental are useless.

    The above is a general comment on differential and incremental archiving and is not to be taken as a Paragon specific discussion.
     
  3. ratchet

    ratchet Registered Member

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    You did an excellent job of explaining that and I thank you!
     
  4. John Doe Genius

    John Doe Genius Registered Member

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    From my test in real life, I can confirm what seekforever estimated; please read https://www.wilderssecurity.com/showpost.php?p=2158731&postcount=15
    :thumb:
     
  5. seekforever

    seekforever Registered Member

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    Thanks for the confirmation!
     
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