Re: Memory

The 'rule of thumb' ratio of memory to swap space varies depending on who you talk to :

                SWAP : MEMORY
                   2 : 1
                   3 : 1(the one I have used)
                   4 : 1

ORACLE support told me that swap space needs to be allocated by ORACLE processes even if there is enough real memory to meet your requirements. ÝI.E. swap space must be allocated even if it is not used ¨

From monitoring systems is the past, I have noticed that the use of swap space increases as more ORACLE processes are started, however the monitoring software (e.g. SAR) can show that NO swapping is taking place. Ý On various UNIX implementation including SCO ¨ I must confess that I don't fully understand why this should be so!

As it is often easier to allocate additional swap space than to obtain additional real memory, I would try allocating in the 3:1 ratio (48Mb swap for 16Mb real memory).

Use 'sar -r' to report on swap space and real memory allocation and
'sar -pqw' (I can' remember exactly which options) to see if swap space is
allocated but no swapping is taking place.

The anomaly still remains:
  IF YOU ARE CURRENTLY SWAPPING BECAUSE YOU DO NOT HAVE ENOUGH REAL   MEMORY, YOU SHOULD ADD MORE REAL MEMORY.   BUT, ONCE YOU HAVE INCREASED YOUR REAL MEMORY YOU SHOULD INCREASE   YOUR SWAP ACCORDINGLY.
  Ýi.e. by reducing/removing the need for swapping

        you increase the swap space required ¨

If anyone can else can explain this anomaly, or show me any errors in my understanding, I would be grateful.

In the meantime, try increasing your swap space (if possible) based on
'blind faith'.

Regards, Kevin.

Kevin Johnson                      EMAIL  :  johnson_at_mail.esrin.esa.it
Information Administrator
European Space Agency              DISCLAIMER :  These views are mine
ESRIN, FRASCATI, ITALIA.                         not necessarily those
                                                 of my employer
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