How to Prefetch Using Disk Cache for Motion Tracking

Hello everyone,

I’m trying to prefetch my video for motion tracking using disk cache option but Blender doesn’t use it. It still prefetches using memory (RAM). How can I use my disk space for prefetch cache?
I saved my preferences and Blender file, relaunched the project and hit the prefetch button but still using RAM and prefetches only small part of video (I have low RAM, 8GB). I tried both 2.92 and 2.93 Blender versions but same results.

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