Differential vs Incremental

Discussion in 'Acronis True Image Product Line' started by jimnye, Aug 14, 2006.

Thread Status:
Not open for further replies.
  1. jimnye

    jimnye Registered Member

    Joined:
    Aug 13, 2006
    Posts:
    9
    I am a new user of TI (v9 3677). I have TI on each of my 3 networked computers and use a 250GB WD external drive as my backup place.
    I have made a full backup of each computer's C: drive and have done a daily differential backup in each case. I still have plenty of room but that will dissappear fast so was wondering about deleting some of the differentials, as the instructions suggest that with Incremental Backup all copies are needed for disaster recovery but that with Differential Backup only the last Differential and the original Fullbackup are required. The main computer (the one the external is attached to) has a fullbackup of 14GB and differentials of about 2.1 and growing. The other two are about 4GB and 307MB each. The large one and one small are running XP2 and the third one is running ME.
    Answers please.

    Jim
     
  2. bVolk

    bVolk Registered Member

    Joined:
    Dec 22, 2005
    Posts:
    954
    jimnye,

    If you are tight on space, incrementals would be better, in my opinion.

    Within a series of differentials, the data recorded in any differential image will be recorded again in every subsequent differential (broadly speaking), wasting disk space if you keep them all. You should also keep in mind that due to a bug, to validate the n-th differential all the previous differentials should be present, though for restore they are not needed (if you don't care to have previous points in time available for restore).

    Edit: See also Acronis Support post of today in this thread
    https://www.wilderssecurity.com/showthread.php?t=140334#post817711
     
  3. jimnye

    jimnye Registered Member

    Joined:
    Aug 13, 2006
    Posts:
    9
    Thanks bVolk.
    I take it then that I could do an incremental, now, referring to the original fullbackup and then each one referring to the previous incremental?
    I will only do this until the verifying bug is fixed because in terms of simple restoration differential seems to win hands down, not only because of the alledged less time but also because the more files to trawl through the greater the risk of mistakes

    Jim
     
  4. bVolk

    bVolk Registered Member

    Joined:
    Dec 22, 2005
    Posts:
    954
    Hi again jimnye,

    In fact, to create a new incremental as an addition to some existing ones you may select any file in the chain (including the starting full) and TI will recognize it as Volume X of a Multivolume Archive and append the new incremental to the last incremental of the existing string.

    The same goes for validating: you may select any one file and TI will validate the whole chain. And for restore, you select any one file again and on the next screen you are presented with the whole series of restoration points to choose from. After you select the restore point, TI will automatically include the proper files in the restoration.

    As for the corruption risk I doubt if you will be any safer with differentials. Compare a set composed by a full and 6 incrementals to a set composed by the same full and a differential created at the same time as the 6th incremental above. The 6 incrementals toghether will carry the (broadly) same amount of data as the single differential in the other set (same amount of risk, since it's the number of bytes exposed to corruption that counts, not the number of files). If one byte goes bad in the differential, you are left with the full image only. If one byte goes bad in one of the incrementals, all the restore points belonging to the incrementals earlier to the corrupt one will be available (after you locate the corrupt incremental file and delete it and the subsequent ones).

    That's my view (it may not stand if large files are created and deleted from the HD in the meantime) but I'll be glad to hear another opinion.
     
    Last edited: Aug 14, 2006
  5. jimnye

    jimnye Registered Member

    Joined:
    Aug 13, 2006
    Posts:
    9
    Hi BVolk

    Your argument looks logical to me and I can see why incremental is fine. I mistakenly assumed numbers of files may be a problem. Infact I was just going with the programme's own recommendation.

    I have run my shop for the last 23 years without a proper safety net, although I have, of course, run programme back ups but only to the respective HDs. My system runs 24/7-365 so I have always updated my pcs or HDs every few years and never lost any data - but there is always a first time so this is why I did some research and settled on Acronis.
    oops It must be my age - I have just remembered I did once use a DAT drive which I found useless beacause the tapes stretched after only a year's use and I have also used Iomega Zip drives which have been less than reliable. I hope the WD book and Acronis prove reliable in the event of a HD failure.

    Thanks again for your help and interest

    Jim
     
  6. bVolk

    bVolk Registered Member

    Joined:
    Dec 22, 2005
    Posts:
    954
    You are welcome, jimnye,

    You may want to have another look at the thread I referred to above to see the clarifications that followed. So that you won't be left with incorrect information.

    I'm sure True Image will make you sleep better while that poor thing of yours will be running. :D
     
  7. jimnye

    jimnye Registered Member

    Joined:
    Aug 13, 2006
    Posts:
    9
    Verrry Interrresting (sic Re: Best way to remove old backup files?).
    Nearly the same question as mine.
    It is a great little programme, though,(Acronis TI9). Over the years I have run business programmes costing many hundreds more and which don't quite do everything it says on the tin. In fact, for my EPOS system, I was a beta tester for a number of years because the only way to thoroughly prove a programme is in the real world with users trying to get it to do what they expect it to do. I do feel a little sorry for the deveopers at Acronis but I reckon if I was either 'A' or 'A' then I would be squirming quite a bit with comments made by you guys.

    enjoying the debate

    Jim
     
Thread Status:
Not open for further replies.