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When copying files from/to my external USB3 HDD memory usage in Win7 goes up to 100% and remains there. I'm not sure whether this is a problem caused by faulty drivers or not, but I already have the current version of them (Etron USB3 controller on a Gigabyte 990fxa board)..

Using RAMMap it becomes obvious that the files, that are to be copied, are mapped into memory. Clicking on

Empty > Empty System Working Set

seems to temporarily fix the problem (without causing any trouble with the file copy process), but it needs to be done every few seconds. Is there any way to schedule this operation to happen ever 10 or so seconds on its own? What underlying system command is RAMMap using? Or, alternatively, is there any way to limit how much RAM mapped files may use in Windows 7?

I know mapped files would usually be removed from memory if other programs need the memmory, but while memmory usage is at 100% the system starts freezing up for half a second or so everytime I click anything .. thus the automatic removal of unused memory contents seems to be failing here.

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Since Vista, there's an optimisation to fill unused memory with files buffers. When your application requests memory, the OS will automatically flush these buffers. It's pointless to have "free" memory when they're doing nothing but using the same amount of electricity. – Sep 10 '12 at 19:05
When the system starts freezing up its obviously way past any optimizations - and needs fixing. – Dexter Sep 10 '12 at 20:07
Use XCOPY with the /J switch as a workaround, but I suspect your USB drivers are faulty. – user3463 Sep 11 '12 at 6:55
@RandolphWest: Is there any way to set that option in SyncToy? – Dexter Sep 11 '12 at 18:29
SyncToy is a front-end for Robocopy, and as far as I know, Robocopy does not support the /J feature. – user3463 Sep 11 '12 at 22:20
up vote 2 down vote accepted

I guess this is a complex issue. Part of the problem is most certainly the drivers, but the other parts are SyncToy/robocopy and Truecrypt (the USB3 drive is encrypted) - the issue does not manifest itself when just copying files with Ctrl+C/V. The RAM still fills up with the mapped file of the Truecrypt container, but the usage does not show up in the Task Manager (only in RAMMAP) and the system does not freeze up.

So MS, Etron/Gigabyte and the Truecrypt folks probably all deserve some of the blame for this..

Either way, after years of pain, I finally found a simple solution to the issue, thanks to this other Superuser thread about Windows screwing up with its filecache, leading to this discussion on the Sysinternals forum, finally leading to someone having created a tool ("SetSystemFileCacheSize") that essentially just calls the windows API to end this nightmare. ( much for Windows working as intended

Usage is fairly simple: SetSystemFileCacheSize off 2048 fixes it for me. First argument is the lower limit to cache, second argument the upper cache size limit. Depending on how much memory one has other values may make more sense for them - see the link for more details. There's also a x64 version for values beyond 4G.

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Install the Service "Microsoft Windows Dynamic Cache Service" this allows you to configure the file cache. To get the Win7 / Server 2008 R2 version, contact the support.

You experience performance issues in applications and services when the system file cache consumes most of the physical RAM

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I tried contacting M$ for this tool and they wouldn't give it to me unless I paid up for a support case first. Any other suggestions? – BeowulfNode42 Sep 3 '13 at 4:45
if this is so urgent pay the support. – magicandre1981 Sep 3 '13 at 15:57

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