RE: Does NT write to random locations on disk?

This just goes to show how little I know, good grief it never ends.

Thanks for the responses.

: )

Patrice Boivin
Systems Analyst (Oracle Certified DBA)

Systems Admin & Operations | Admin. et Exploit. des systèmes
Technology Services        | Services technologiques
Informatics Branch         | Direction de l'informatique 
Maritimes Region, DFO      | Région des Maritimes, MPO

E-Mail: boivinp_at_mar.dfo-mpo.gc.ca <mailto:boivinp_at_mar.dfo-mpo.gc.ca>

        -----Original Message-----
        From:   Dennis Taylor [SMTP:ismgr_at_pctc.com]
        Sent:   Friday, March 09, 2001 7:26 PM
        To:     Multiple recipients of list ORACLE-L
        Subject:        RE: Does NT write to random locations on disk?

        At 01:55 PM 3/9/01 -0800, you wrote:


        >Oracle datafiles are formatted into blocks.  Data is read either

physically


        >by block or an indexed block number.  If you compress using zip and

then


        >uncompress, the blocks have not changed.  If you reorg the file the

blocks


        >will probably change and the data wont be where Oracle thinks it

is.


        >


        I'm working from logic rather than specific knowledge of Oracle
here, so I
        could be way off base. But if you are set up to use a cooked rather
than
        raw file system, then the block number that Oracle uses should be
        file-relative rather than disk-relative, i.e. the block labelled
'34' would
        be the 34th or 35th block *in the file* rather than *on the disk*.
No
        matter how much you defrag, zip, unzip, copy, mash, spit on, or
otherwise
        vilify the file, it still ends up with the same data in that block.
        Theoretically.


        Dennis Taylor
        --------------------------------
        ILLEGITIMUS NON CARBORUNDUM.

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Author: Boivin, Patrice J
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