Re: Large SGA in Solaris

  • From: David Miller <David.J.Miller@xxxxxxx>
  • To: sacrophyte@xxxxxxxxx
  • Date: Fri, 08 May 2009 10:09:31 -0500

Hi Charles,

I don't believe that is true.  Swap on Solaris is swap.  It doesn't
differentiate between free memory and disk space.  However, you do
need to have enough swap space to map the whole DISM segment when you
start up, so you'll need memory for DISM + another amount in swap.
With a 50 GB SGA, you'd need 100 GB total between disk and memory.
You might check "swap -s" before and after starting up to see how
much space you have and how much you need.

I'm not sure what you mean by "throwing up some ramfs".  If you mean
adding space to /tmp, which is tmpfs or creating another tmpfs filesystem,
that space comes directly out of swap.  So you'd just be allocating a
temporary filesystem from the same space you supposedly want to use for
swap.  Needless to say, that doesn't create any more space, just redistributes
the space already there.


Dave Miller

Charles Schultz wrote, On 05/08/09 07:15:
Just to add to that, the swap space for DISM has to be backed by disk. We found this through trial and testing. =) Just throwing up some ramfs is not good enough. I am not exactly sure why this is, as I have not yet fully understood the whitepapers that Sun and Oracle both provided.


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