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Windows XP, External USB, Large File Copy - Last Modified 2008-09-26 21:04 UTC - Created 2008-09-26 21:04 UTC

So I was copying some large files (2GB+) from my computer to an external usb hard drive. The filesystem on the usb drive is NTFS. I ran into a problem where my computer was getting very slow.

It turns out my available memory was running all the way down to zero. This only happened while the large file copy was in progress. I was using xcopy to move a bunch of files over.

After searching for possible clues as to what would cause the issue I discovered that my Windows "System Cache" was growing to over 2GB. This cache is responsible for caching among other things files from the filesystem.

So I tried disabling anti-virus, write caching, and registry adjustments. That did not help.

I then found a tool that will let you temporarily reset the size of the system cache to a value you specify. You can't force a permanent maximum (except in Windows Server 2003 or later), but you can call it via a scheduled task if desired. It takes affect immediately and relieves the memory issue.

The tool is called CacheSet and can be obtained from Microsoft (SysInternals).

It isn't a perfect solution since you have to keep running it to keep the cache size down, but it is better than nothing at all.