Re: swap/memory ratio

Well, don't do the swap as I said if you are ever going to be using swap, it's one of the slower ways for swap to work. If you know you are going to swap, use your faster device with primary swap.

If you are swapping at all, you will likely be suffering from in-the-users-faces performance issues. You would be better off to use a single instance and small SGA if you can't increase physical memory.

What's the problem with increasing the ram? Is it more than a fraction of your yearly pay (or more than US$1000/G)? Which hardware are you using, exactly? _Planning_ on using swap for OLTP is a mistake, unless you only have a couple of actual users at a time (and even then, any time a connected inactive user becomes active again, there will be a huge wait while Oracle and the OS and the storage system bicker about it).

If cutting down the pga_aggregate_targets lessen swapping, that won't decrease the performance, to put it mildly. That's exactly what I've seen with multiple instances. Remember, most advice Oracle docs give assumes a single instance per server. All that swapping stuff was more appropriate to the last century when memory cost more than people.

jg

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@home.com is bogus.
DRAM pricing is all fixed anyways.
http://www.signonsandiego.com/uniontrib/20051201/news_1b1samsung.html