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I would like to span my Windows 7 pagefile across a 2nd disk, but I would still like that disk to be able to power down when idle (and when virtual memory use < physical memory size).

Are these two requests mutually exclusive on the same physical disk?

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spanning a page file on multiple disks is designed for performance improvement.

You will have no control on how (and to which disk) Windows will page out data, and how/when it will be retried.

If you need performance, increase the disk pool available to the page file.

If you need power savings, don't.

You can't have both.

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What about if my virtual memory use stays below my physical memory size for x period of time? – DuckMaestro Oct 10 '11 at 21:46
@DuckMaestro That question doesn't make sense. VM is used when Windows deems it want more free physical memory. You meant what if my memory use remains less than physical RAM? It doesn't matter. I have 16GB of RAM, of which only 5GB is actually in use. Windows has paged 1GB of Kernel to the disk and who knows what in Userland. You don't have a choice, it's all run by black magic. The whole point of this topic is moot. If you want a sports car you don't get fuel economy. – Dom Oct 15 '11 at 11:51
I think there's a terminology mismatch here. In operating system terminology, VM is exactly that, virtual memory. VM does not always equal use of the page file. An app resting entirely in RAM is also resting in VM. Also, it's not a moot question a priori. You seem to have additional knowledge on the subject, but a priori, it's reasonable to ask whether under some use cases (only a web browser open) the disk would sleep while in other use cases (Photoshop, Blender, etc open together) memory might obviously page and prevent disk sleep. – DuckMaestro Oct 15 '11 at 19:39

Most probably, placing the pagefile on the 2nd disk will make it less likely to power down as it there will be less occurrences of it being idle. If you are looking for power savings, you should place the pagefile on the same hard disk as the OS itself. However, you can consider using a different partition to store it.

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"Most probably, placing the pagefile on the 2nd disk will make it less likely to power down." -- Are you saying it will nevertheless still have the opportunity to power down under certain conditions? – DuckMaestro Oct 10 '11 at 21:47
@DuckMaestro I have been testing this, and in windows 7 the paging file on the second disk is being accessed enough that my 40-60min spin-down settings are insuring that drive never spins down, it was a specific array that could and did. I can not be positive in all circumstances for all systems, but I would confirm that "most probably" is accurate. Information based on viewing resource monitor, and knowing when the drives have to spin back up. – Psycogeek May 5 '12 at 15:10

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