Solaris

Hi

Can any help me on setting the swap memory ? I would like to set swap memory for installing oracle 9i software.

RAM - 512 Mb
HDD - 40 Gb
OS - Sun Solaris 5.9

Hi,

Usually ( dependes on the DB function and load ), oracle processes need large virtual address spaces, so I would recommend at least the double of the physical memory... but for a good tunning, you need to pay attention to other parameters, like shared memory, semaphores, etc... and these things are very different if you're using 32 or 64 bits.

Thank you for your input.

yes I am planning to install oracle 9i 32 bit -

Jsilva is right,
depends how "busy" your Oracle DB will be.
Anyways, 2 and 1/2 times the phisical memory it's a good formula, I have never had issues.

virtual mem=2x real memory should be your default upto 1 or 2 gb.

this is the way i have always read in various system books for various OS and is pretty consistant with what i have heard around the net.

"virtual mem=2x real memory"
i often heard this opinion, and also used it for some years. but this rule is very old i think and based on mashines with less memory. i'm working as an sunse and my "work" is often based on 16 to 32 GB RAM (or sometimes more) mashines, so you have to explain your costumers why should he have a swap base with 2x real memory..... you cannot spend 2 disks only for memory; there is 32 GB memory waiting for some work....
my way:
i use the same size of memory for swap, otherwise you won't survive a memory dump, and 1 GB for swap paging. i haven't got any problems since this new calculation.

greetings Preßy

Preßy, there is some truth to what you're saying. But 2x memory is still a good calculation. Let's take one step at a time.

Before risc, 32 K was a common memory size and 512 K was a lot of memory. In those days, unix would not allocate a page of memory unless it could also allocate swap for it. If you had 32 K memory, you needed 32 K of swap just to use it all. If wanted to be able to use more than 32K of memory on your 32K machine, you needed 2 or 3 times the swap space. This was not seen as a problem. Disks were very big compared to memory.

Risc changed things. Suddenly we had 32 MB of memory and 300 MB disks. Two to three times memory was a big deal. Someone noticed that a kernel would never swap everything out leaving memory empty. So various schemes were implemented to change that way things work. You can now have 1 GB of memory and .5 GB of swap and things will work. There is a price for this which varies from OS to OS. And you may need to tune the kernel to get it to work.

But disks have caught back up with memory. The old ratios have been matched and even surpassed. 1 GB of memory is a lot. But 2GB of swap is small change. Even my laptop has an 80 GB disk.

Running out of swap is still a disaster. So yes, with modern equipment 2 or 3 times memory is good again. If you have a early 90's system, this won't be true for you. But it's time to upgrade those 500 MB washing-machine-sized drives anyway.