What is secure virtual memory on Mac? To keep your information safe, macOS uses secure virtual memory. Virtual memory is a technique computers use to temporarily move data from random-access memory (RAM) to the hard disk if the amount of available RAM is limited. If the data written to the hard disk as virtual memory is unencrypted, and is never overwritten, it could be captured if the hard disk is scanned, creating a potential security risk. Secure virtual memory in macOS eliminates this risk by encrypting the data in virtual memory. Secure virtual memory is always on, so data is kept secure while it’s swapped between your hard disk and RAM. The RAM on your Mac contains no information when it’s turned off.