A non-negative synonym for "unused" or "untouched" that doesn't have the sexual implications of "virginal"

Solution 1:

pristine (adj.)

In its original condition; unspoiled.

pristine copies of an early magazine

Immaculately clean and unused

handed her his pristine white handkerchief vocabulary.com

All the media used to store the findings must be pristine, previously unused media. Chey Cobb; Network Security For Dummies

Taking a hard disk from its pristine, newly manufactured state to a fully functional DOS or Windows 95 storage area ... Neil Randall; "Partitioning Your Hard Disks" in PC Magazine

Take a "clean slate" approach to ensure your new, pristine hard drive has a new, pristine copy of Windows on it, rather than a copied- over-and-funked-up Windows image from your old drive. Maximum PC, 2005, p.32

Solution 2:

Good question!! In my experience in IT, we would often use the term “empty” to describe unused disk or data space with our clients in other departments.

Here is how “empty” has been used on Quora:

“… when a file is deleted or put in the recycle bin, [the file] is not deleted, but instead, the disk space is marked as empty …”

Sure, you’re not talking about file deletions as in that quote, but might “empty” work for your purpose? Best of luck with your project!