Differential vs incremental

Discussion in 'Acronis True Image Product Line' started by trydit, Oct 14, 2006.

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

    trydit Registered Member

    Joined:
    Apr 3, 2006
    Posts:
    23
    Having completed a full backup, I schedulled a weekly differential backup, which seemed to be the easiest thing to restore not having to use a chain of backups.

    I backup to an external hard drive. When I checked what was on there, I found my original full backup and a whole seriese of backup files of varying sizes (not too different from my orignal backup).

    I thought that a differential backup should just leave one file stored plus the original or have I got this wrong? Is all OK? Which files do I use if I ever want to backup?

    Can someone please explain? Thanks.
     
  2. seekforever

    seekforever Registered Member

    Joined:
    Oct 31, 2005
    Posts:
    4,751
    Each differential backup is kept. This way you can restore to any point in time from the original to the last. Due to a bug in TI9 you can't validate a differential backup unless all of the intermediate differentials are present. To do a restore you just need the original and the appropriate "last" one.

    As far as size, each differential contains all the changes since the original which implies each one could be the same or larger unless files are deleted.

    If your system gets defragged between the original backup and a differential (or incremental), the differential (or incremental) can be very large. This is because imaging programs see any changes in the "in-use sectors" as something to backup - it doesn't matter if the file content hasn't changed.
     
  3. trydit

    trydit Registered Member

    Joined:
    Apr 3, 2006
    Posts:
    23
    Thanks. That explains it well.

    I have a list of tib files, all helpfully numbered in sequence by Acronis, with one having no number, presumably my original full backup. Is it possible to tell if this un-numbered file is my original full backup? The description on the pop-up when pointing to it describes it as "True Image backup archive" just the same as all the numbered sequence of files? This un-numbered file has the earliest date.

    Can I do a differential backup outside of my normal schedule? I've tried this and it seems to launch off on a full backup and take over an hour!
     
  4. TheWeaz

    TheWeaz Registered Member

    Joined:
    Jul 9, 2005
    Posts:
    1,562
    "Can I do a differential backup outside of my normal schedule? I've tried this and it seems to launch off on a full backup and take over an hour!"

    Yes you can. You just need to be sure that the task points to the FULL and is stored in the same location.
    If you run a DIFF and TI cannot find the FULL in the target you designated for the DIFF, it will create a FULL instead.
     
  5. trydit

    trydit Registered Member

    Joined:
    Apr 3, 2006
    Posts:
    23
    Thanks for the advice, that's great. I'll give it a go.

    ...and is it easy to identify the full backup? The earliest dated file, or is there some other way of idetifying it?
     
  6. TheWeaz

    TheWeaz Registered Member

    Joined:
    Jul 9, 2005
    Posts:
    1,562
    The FULL should not have any numbers appended to the name - it should look just as you defined it.
    Example:
    FULL = C_DRIVE_EVEN.tib
    INC = C_DRIVE_EVEN2.tib
     
  7. trydit

    trydit Registered Member

    Joined:
    Apr 3, 2006
    Posts:
    23
    Many thanks. My understanding is growing! I have a file with no apended numbers stored on my external hard drive, that must be the full.

    And some explanation of "Active Tasks" would be great as well if that's OK?

    There are three "tasks" shown.

    First task:
    Name: "Invalid script file"
    Status: At 19:00 every week on Thurs.
    Schedule: At 19:00 eevry week on Thurs
    Last run time: 19:02
    Last result: Completed successfully

    Second task
    Name: New backup
    Schedule: No value
    Last run time: No value
    Last result: No value

    Third task
    Name: "Invalid script file"
    Status: At 19:00 every week on Thurs.
    Schedule: At 19:00 eevry week on Thurs
    Last run time: 20:30:44
    Last result: No value.

    The third task is in progress and the % counter is tracking its progress. Have I unwittingly started another backup!?
    When you say "the task points to the FULL and is stored in the same location", does that mean I highlight an active task or if not how do I "point" to it?

    Many thanks.
     
  8. TheWeaz

    TheWeaz Registered Member

    Joined:
    Jul 9, 2005
    Posts:
    1,562
    When you set up a scheduled task (even if you select “Do not start automatically”) will show up in the Active Tasks window.

    “Have I unwittingly started another backup”

    I would have to guess, yes.
     
Thread Status:
Not open for further replies.