Deleting files on NAS using Windows 10

I have been using the NAS for awhile now and I need to start to delete duplicate files.All files have come from my Windows 10 machine. I delete from Windows but the file size on NAS stays the same.


I have no idea how snapshots work? Sorry so new to this storage device.

If you created a snapshot on the TrueNAS machine at some point in time then this “stage of files” is preserved in the snapshot. When you delete files after creating the snapshot (doesn’t matter if you do that from a client machine or on TrueNAS itself using midnight commander for example) then the files are deleted from a client perspective.
On TrueNAS the files’ data is still there: in the snapshot. You could return to the point in time when the snapshot was created and the files would be accessible again.

Have you created a schedule for automatic snapshot creation?
You could just delete the snapshots of the corresponding dataset(s) and the space would be freed, then by really deleting the file content. A file recovery is not possible after deleting the snapshot(s).

ZFS snapshots are both a simple recovery technique, and ransomware protection. Any file in a snapshot is frozen in time, until the snapshot expires. (Or not, as you can manually create a snapshot that does not expire.)

The way encrypting ransomware works, is by encrypting files. If the file was available at the time of a snapshot, then the ransomware is actually making a new file. That takes up space and a fullish NAS will fill up completely, sort of notifying the user of the problem.

But, as long as any snapshot exists that covers the file(s) you want, they can be restored.