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Thread: Backups - Basic Qs

  1. #1
    Join Date
    Nov 2014
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    5

    Backups - Basic Qs

    Hi;

    I've researched elsewhere, however haven't found clear answers to the below.

    I refer generally to SQL Server 2008 R2.

    These are to aid my learning. Short, simple answers preferred if possible.

    More to follow, soon.

    Thanks in advance.


    - What is the benefit(s) of striping, and why - performance?
    - Where does the backup media set header 'live' - is it present on all of the backup media in the set?
    - What does the *name* of the command, 'init' mean - pertaining to instant file initialisation?
    - How does the 'compression' command enable faster backups and restores?


    J

  2. #2
    Join Date
    Sep 2002
    Posts
    5,938
    1. yes, backup to multiple files are faster than to single file. But no need for small dbs.
    2. depends on what kind of media.
    3. init option means overwrite existing backup media.
    4. compression option compresses data during backup therefore faster, not much for restoration.

  3. #3
    Join Date
    Nov 2014
    Posts
    5
    Thanks for the reply, rmiao.

    To clarify my questions:
    1. Why is backup to multiple files faster than one - is there not an overhead?
    2. Disk drive files, for example?
    3. What is the etymological significance of the name 'init'?
    4. How does compression make this faster?


    J

  4. #4
    Join Date
    Sep 2002
    Posts
    5,938
    1. because parallel writing, faster that write to single file.
    2. never heard 'live' header.
    3. means initial.
    4. write less to backup file.

  5. #5
    Join Date
    Nov 2014
    Posts
    5
    That's great.

    Regarding Q2: Can you give examples of where a backup media set header resides for a media set (any) - for example, when you query the header (I think using the 'restore' command), where is the result set drawn from?


    J

  6. #6
    Join Date
    Sep 2002
    Posts
    5,938
    If you are talking about 'restore headeronly', info is stored in backup file which you mentioned in 'disk =' part.

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