SPREADING CONFUSION

Discussion in 'MCSA' started by dawnad, Oct 9, 2005.

  1. dawnad

    dawnad Guest

    I came accross this question on a website that i consider to be helpful,
    however, this question and their own answer has thrown my confidence into
    doubt. I need some perspectives please.

    The question:

    You want to perform multiple backups of only those files that are modified
    since the last normal backup. You also want to ensure that the backed up
    files use minimum amount of media. In this case, you will take a:

    1. Normal backup
    2. Differential backup
    3. Incremental backup
    4. Copy backup

    Thier answer is Incremental backup. I think it is Differential. What do you
    think?


    dawnad
     
    dawnad, Oct 9, 2005
    #1
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  2. I thought it was Differential as well.

    If I'm not mistaken, an Incremental backup will backup any files that have
    changed since the last normal backup and reset the archive bit. A
    Differential backup will backup all files that have changed since the last
    normal backup, but not clear the archive bit. Thus you can run a diff
    backup right after each other, and they would backup the same files, thus
    the "You want to perform multiple backups of only those files that are
    modified since the last normal backup."

    I may be wrong though.


    "dawnad" <> wrote in message
    news:D...
    >I came accross this question on a website that i consider to be helpful,
    > however, this question and their own answer has thrown my confidence into
    > doubt. I need some perspectives please.
    >
    > The question:
    >
    > You want to perform multiple backups of only those files that are modified
    > since the last normal backup. You also want to ensure that the backed up
    > files use minimum amount of media. In this case, you will take a:
    >
    > 1. Normal backup
    > 2. Differential backup
    > 3. Incremental backup
    > 4. Copy backup
    >
    > Thier answer is Incremental backup. I think it is Differential. What do
    > you
    > think?
    >
    >
    > dawnad
     
    Ryan Headrick, Oct 10, 2005
    #2
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  3. Bob,

    What you said is incorrect when it comes to differential backups.
    Differential backups do not clear the archive attribute. So given the
    following scenario:

    Monday morning: full backup
    Tuesday night: differential backup
    Wednesday night: incremental backup

    the incremental backup backs up everything changed on Monday, Tuesday and
    Wednesday.


    Death from Above


    "Bob Christian" <> wrote in message
    news:...
    > It would be an incremental backup. The incremental backup backs up files
    > which have changed since the last backup, be it a full/nornal,
    > differential, or a previous incremental backup.
    >
    >
    > --
    > Bob Christian II
    > http://bobchristian.blogspot.com - Blog
    >
    >
    >
    > "dawnad" <> wrote in message
    > news:D...
    >>I came accross this question on a website that i consider to be helpful,
    >> however, this question and their own answer has thrown my confidence into
    >> doubt. I need some perspectives please.
    >>
    >> The question:
    >>
    >> You want to perform multiple backups of only those files that are
    >> modified
    >> since the last normal backup. You also want to ensure that the backed up
    >> files use minimum amount of media. In this case, you will take a:
    >>
    >> 1. Normal backup
    >> 2. Differential backup
    >> 3. Incremental backup
    >> 4. Copy backup
    >>
    >> Thier answer is Incremental backup. I think it is Differential. What do
    >> you
    >> think?
    >>
    >>
    >> dawnad

    >
    >
     
    Death from Above, Oct 11, 2005
    #3
  4. dawnad

    dawnad Guest

    Remember, the question said "minimum amount of media".

    Lets say you do a normal backup of 10 files of 10MB each on monday totalling
    100MB.

    On tuesday, 5 files change. Running either incremental or differential
    backups will both total 50MB of media.

    Lets say that three files change on wednesday and two of those are among the
    ones that changed the previous day.

    An incremental backup of the previous day (tuesday) and that of the current
    day (wednesday) will total 50MB + 30MB = 80MB since incremental resets the
    archive bit.

    On the other hand, since it does not reset the archive bit, a differential
    backup of tuesday will be 50MB and that of wednesday will be 60MB wich is
    just 10MB bigger. This is because two of the files have also changed the
    previous day (tuesday) giving a total of six files that have changed since
    the last normal backup.

    Considering the above, the incremental backup consumed more media so I still
    maintain that the answer to the question is a differential backup.
    --
    dawnad


    "Bob Christian" wrote:

    > Death:
    >
    > I respectfully stand corrected.
    >
    > Bob
    >
    > --
    > Bob Christian II
    > http://bobchristian.blogspot.com - Blog
    >
    >
    >
    > "Death from Above" <> wrote in message
    > news:%...
    > > Bob,
    > >
    > > What you said is incorrect when it comes to differential backups.
    > > Differential backups do not clear the archive attribute. So given the
    > > following scenario:
    > >
    > > Monday morning: full backup
    > > Tuesday night: differential backup
    > > Wednesday night: incremental backup
    > >
    > > the incremental backup backs up everything changed on Monday, Tuesday and
    > > Wednesday.
    > >
    > >
    > > Death from Above
    > >
    > >
    > > "Bob Christian" <> wrote in message
    > > news:...
    > >> It would be an incremental backup. The incremental backup backs up files
    > >> which have changed since the last backup, be it a full/nornal,
    > >> differential, or a previous incremental backup.
    > >>
    > >>
    > >> --
    > >> Bob Christian II
    > >> http://bobchristian.blogspot.com - Blog
    > >>
    > >>
    > >>
    > >> "dawnad" <> wrote in message
    > >> news:D...
    > >>>I came accross this question on a website that i consider to be helpful,
    > >>> however, this question and their own answer has thrown my confidence
    > >>> into
    > >>> doubt. I need some perspectives please.
    > >>>
    > >>> The question:
    > >>>
    > >>> You want to perform multiple backups of only those files that are
    > >>> modified
    > >>> since the last normal backup. You also want to ensure that the backed up
    > >>> files use minimum amount of media. In this case, you will take a:
    > >>>
    > >>> 1. Normal backup
    > >>> 2. Differential backup
    > >>> 3. Incremental backup
    > >>> 4. Copy backup
    > >>>
    > >>> Thier answer is Incremental backup. I think it is Differential. What do
    > >>> you
    > >>> think?
    > >>>
    > >>>
    > >>> dawnad
    > >>
    > >>

    > >
    > >

    >
    >
    >
     
    dawnad, Oct 12, 2005
    #4
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