On May 9, 8:47=A0am, bho****r <bhona...@[EMAIL PROTECTED]
> wrote:
> > The question I have is, is there any downside to me buying, say, a 32G
> > box and setting the SGA size at 20G? Will I actually end up harming my
> > performance with an over-large SGA (assuming I have enough physical
> > memory to keep the box out of swap)?
>
> Since everyone is busy telling you how to tune instead of answering
> your question, you might have to infer that the answer is "No, there
> is no downside to adding memory." =A0That's my takeaway from no
> negatives pointed out anyway...
Then you're not reading the entire thread, as I posted that installing
all of the physical memory a server can accept, then allocating 80% of
that to the database would be wasteful, to say the least. Knowing
that this is a Windows operating sytem, which requires 2 gig for the
operating system alone, may make that 80% allocation 'impossible' thus
creating a scenario of constant paging/swapping to/from disk. Of
course even a successful allocation of that much memory to the SGA
would create a paging/swapping situation as PGA components may require
more free memory than is available. Which, in turn, sends performance
into the proverbial dumpster.
Even if he's lucky and no paging occurs it's highly likely his memory
allocations will be unused as constantly changing data causes the
cache to be refreshed from disk, thus killing the 'benefit' of having
all of those lovely data blocks in cache. And bloating the SGA to
starve the O/S is ... not the wisest of moves.
The negatives of this situation are known by most of those who have
posted to this thread. Siimply because you can't see them in print is
no indication they don't exist.
David Fitzjarrell
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