how to estimate the SGA values ?
DBAsupport.com Forums - Powered by vBulletin
Results 1 to 7 of 7

Thread: how to estimate the SGA values ?

  1. #1
    Join Date
    Oct 2002
    Posts
    284

    how to estimate the SGA values ?

    Hello all...

    Sun 5.8 / Oracle 9.2 and Oracle8.1.7

    This is one question that always have at the back of my mind ...

    How do we estimate the size of the SGA ?.....Like say when i created a database using DBCA, it already assigns some default SGA values.

    Is there a "Rule of Thumb" for assigning SGA values for each instance..?...Most of my databases have atmost 25-50 connections at a given time with about 1GB data. ...

    How do we calculate the SGA values for these kinds of Databases ?...

    currently i have values ranging from :
    320,308,312 to 48,075,571

    So can anyone pleas expalin how to estimate the SGA values ?


    Thanks
    Ron

  2. #2
    Join Date
    Dec 2002
    Location
    USA
    Posts
    53
    It's mainly depending on how much real memory in your box. General speaking, do not allocate >60% of your box memory for SGA.

  3. #3
    Join Date
    Oct 2002
    Posts
    284
    Sun 5.8/Oracle 9.2

    So for eg. If my Physical RAM is 1GB and i have 4 Instances each with 400MB and if my SWAP AREA is 1GB....what happens ?...

    Will it stop loading from 3rd instance since 800 MB already used for Loading the First 2 Instances ?...
    Iam new to DBA and iam trying to figure out the MAth here ...
    Thanks

  4. #4
    Join Date
    Dec 2002
    Location
    USA
    Posts
    53
    The 3rd instance will start and the box will have a lot of PAGING.... make system slow....

  5. #5
    Join Date
    Oct 2002
    Posts
    284
    Iam Sorry ...Iam new to DBA ...

    So what are my Options to make it work better ?....Increase RAM ?...or SWAP Area ?....

    Thanks
    Ron

  6. #6
    Join Date
    Sep 2001
    Location
    NJ, USA
    Posts
    1,287
    Originally posted by vr76413
    Iam Sorry ...Iam new to DBA ...

    So what are my Options to make it work better ?....Increase RAM ?...or SWAP Area ?....

    Thanks
    Ron
    One of the main rule for dba:
    SGA should be in REAL memory and NEVER in swap.

  7. #7
    Join Date
    Dec 2002
    Location
    USA
    Posts
    53
    Increase RAM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


Click Here to Expand Forum to Full Width