Space Usage inconsistent for Temp (Unix)
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Thread: Space Usage inconsistent for Temp (Unix)

  1. #1
    Join Date
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    Question Space Usage inconsistent for Temp (Unix)

    Hi everyone...
    Okay - I've got a strange one for you. A friend asked me

    Does anyone have any nifty tool or suggestion that helps provide visibility into how Oracle tempfiles really look from the Unix OS standpoint. I'm particularly concerned with the fact that, on Solaris at least, when using either the "df" or "du" utilities, what apparently shows up is the current "real" size of the tempfile, regardless of the number of bytes it was defined to occupy when it was created with a "create temporary tablespace ... tempfile ..." statement.
    I, of course, said to myself... that's not true on AIX. But I have found some strange results. (all sizes are in MEG)

    Code:
    
             Size of                                         TEMP
             ALL Files     ls -l       du -m      TEMP       size
             in Dir.    temp01.dbf  temp01.dbf  filesize     Used
            ----------  ----------  ----------  ---------  ---------
     SYS1     9,682.47    9,504.02    9,504.12   9,504.00   7,168.02 
     SYS2       176.96       10.01       10.01      10.00       2.31 
     SYS3       102.73      100.01 	      2.83     100.00       1.00
    SYS1 is 8i, SYS 2 & 3 are 9i. All are on AIX 5.2
    WHY?? would du return only "used" bytes? And why on only 1 of the systems. I'm at a loss.

    What am I missing?

    Any insight would be appreciated!
    Thanks!
    Jodie

  2. #2
    Join Date
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    I don't know. I see the same phenomenon. I saw an article on sparse files on Metalink. Am not sure if it's relevant.

    Do a "file" on the tempfile on SYS3. Does it show up as ascii text?

    PS : Humor me - is your segment space management set to 'AUTO' on SYS3 and MANUAL on SYS1, SYS2?
    Last edited by Axr2; 06-02-2005 at 04:15 PM.

  3. #3
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    Originally posted by Axr2
    I don't know. I see the same phenomenon. I saw an article on sparse files on Metalink. Am not sure if it's relevant.

    Do a "file" on the tempfile on SYS3. Does it show up as ascii text?

    PS : Humor me - is your segment space management set to 'AUTO' on SYS3 and MANUAL on SYS1, SYS2?
    Hi Axr2!
    A "file" on the tempfile is ascii on all 3 systems. And Space Management is set to MANUAL (Uniform) on SYS2 & SYS3. SYS1 is still on 8i and is set to Dictionary Managed...yuk.

    Good thoughts though.

    Any other ideas?

    Thanks!
    Jodie

  4. #4
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    Does this muddy the waters?

    http://download-west.oracle.com/docs...5a.htm#2063472

    --------------------------------------------------------------------------------
    Note:
    On some operating systems, Oracle does not allocate space for the tempfile until the tempfile blocks are actually accessed. This delay in space allocation results in faster creation and resizing of tempfiles, but it requires that sufficient disk space is available when the tempfiles are later used. To avoid potential problems, before you create or resize a tempfile, ensure that the available disk space exceeds the size of the new tempfile or the increased size of a resized tempfile. The excess space should allow for anticipated increases in disk space use by unrelated operations as well. Then proceed with the creation or resizing operation.

  5. #5
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    thatīs because they are tempfiles, dont you notice tempfiles are created lightining (1 second or so) fast even you specify a large size?

  6. #6
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    Originally posted by dbtoo
    Does this muddy the waters?

    http://download-west.oracle.com/docs...5a.htm#2063472

    --------------------------------------------------------------------------------
    Note:
    On some operating systems, Oracle does not allocate space for the tempfile until the tempfile blocks are actually accessed. This delay in space allocation results in faster creation and resizing of tempfiles, but it requires that sufficient disk space is available when the tempfiles are later used. To avoid potential problems, before you create or resize a tempfile, ensure that the available disk space exceeds the size of the new tempfile or the increased size of a resized tempfile. The excess space should allow for anticipated increases in disk space use by unrelated operations as well. Then proceed with the creation or resizing operation.
    dbtoo - Well, at least I know it's a feature, not a bug. Still curious why the systems behave differently though.

    Oh well!

    Thanks!
    Jodie

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