G5 PPC has 2 GB SDRAM but hard drive still acts like it is being accessed for virtual memory - is this normal?

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G5 PPC has 2 GB SDRAM but hard drive still acts like it is being accessed for virtual memory - is this normal?

I recently installed more RAM (this is now a "daily driver" machine for me), yet the hard drive is constantly spinning like it is using virtual memory. I have 2 GB total memory -- 800 MB free and another 800 MB inactive at the moment when I checked -- with 80 GB free on the hard drive.

I upgraded RAM from 512 to 2 GB to get rid of this disk spinning, but no luck (though processing is now MUCH FASTER). Even with very little CPU usage (Safari at 6% usage is the most at the moment) I still have the hard drive whine most all the time.

Is this normal and if not, what can I do to stop / fix it? I checked around on the user support but couldn't find a reference to this specific problem.

1.8 GHz PowerPC G5 (3.0)
CPUs: 1
CPU Speed: 1.8 GHz
L2 Cache (per CPU): 512 KB
Memory: 2 GB DDR SDRAM
Bus Speed: 600 MHz
Boot ROM Version: 5.2.5f1
OS X 10.4.11
ATI Radeon 9600 ATY,RV351

Posted on Jul 18, 2013 3:24 PM

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Answer 1

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Kappy

Level 10

361,741 points

Jul 18, 2013 3:28 PM in response to Jaya7

I hope you understand that hard drives are always spinning. That has nothing to do with vm usage. See:

About OS X Memory Management and Usage

Using Activity Monitor to read System Memory & determine how much RAM is used

Understanding top output in the Terminal

The amount of available RAM for applications is the sum of Free RAM and Inactive RAM. This will change as applications are opened and closed or change from active to inactive status. The Swap figure represents an estimate of the total amount of swap space required for VM if used, but does not necessarily indicate the actual size of the existing swap file. If you are really in need of more RAM that would be indicated by how frequently the system uses VM. If you open the Terminal and run the top command at the prompt you will find information reported on Pageins () and Pageouts (). Pageouts () is the important figure. If the value in the parentheses is 0 (zero) then OS X is not making instantaneous use of VM which means you have adequate physical RAM for the system with the applications you have loaded. If the figure in parentheses is running positive and your hard drive is constantly being used (thrashing) then you need more physical RAM.

Adding RAM only makes it possible to run more programs concurrently. It doesn't speed up the computer nor make games run faster. What it can do is prevent the system from having to use disk-based VM when it runs out of RAM because you are trying to run too many applications concurrently or using applications that are extremely RAM dependent. It will improve the performance of applications that run mostly in RAM or when loading programs.

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Answer 2

Jaya7 Author

Level 1

16 points

Jul 18, 2013 3:42 PM in response to Kappy

Thanks for the info -- especially the ability to view Pageins and Pageouts through the Terminal. I'll check this and see what it says. Yes, I'm aware that the hard drive is always spinning and that VM usage is a function of insufficient RAM to run open programs, not whether the drive is spinning.

As you point out in the last paragraph, before I increased to 2 GB, I'd come close to running out of RAM frequently (multiple programs open) and I could see from the Activity Monitor that (apparently) the system was using disk-based VM because Active Memory was almost the total of what was available, i.e., 512.

I appreciate the clarification and detailed information -- and quick reply. Many thanks.

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Answer 3

Kappy

Level 10

361,741 points

Jul 18, 2013 3:51 PM in response to Jaya7

Understand that running out of memory to the point of using VM, is typically the result of having too many applications running concurrently. With only 2 GBs of RAM to start, deduct Wired RAM, which is used by OS X. This is your maximum available user memory. Without any user applications running some amount of that memory will be used by system processes and will be shown as Active and Inactive. Subtract the Active in use which leaves net user memory. Inactive RAM may never be available for the user depending upon what processes are connected to it. Only Inactive memory not in connected to running processes could be freed to the user. So, frequently, Inactive memory is not usable or usable only on a limited basis.

So, what's left is what your applications can access. Be sure you don't run too many applications that will eat up your Available memory. Some applications like Safari can eat up a lot of Available RAM.

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Answer 4

Kappy

Level 10

361,741 points

Jul 18, 2013 4:40 PM in response to Jaya7

Oh, I forgot to add that OS X memory management improves with each new system upgrade. So moving up to Leopard, 10.5.x. Unfortunately, Leopard is becoming sort of scarce. You will need to look on eBay or Amazon to find copies. Be sure you only purchase a Retail boxed set. Avoid vendors selling so-called "universal installers," or discs that have gray OEM labels.

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