SpiderOak ONE, Groups, and Enterprise treat files on removable media differently from most files. If a file originates with removable media, then SpiderOak backup products will not move their copy of it to the deleted items bin when the removable media is not present.
On Windows, a drive is considered removable if the API function GetDriveType does not return DRIVE_FIXED. CD/DVD drives, USB & firewire devices, and mounted network shares are all treated as removable. If ONE moves its copy of files from removable media to the deleted items bin, that means that the media in question is not properly reporting itself to Windows via GetDriveType. This is a problem with the removable hardware, not with SpiderOak backup. We have seen cases of this but there is nothing that we can do.
On Mac, drives mounted under /Volumes are treated as removable. This is Mac's default location for external media.
On Linux, drives mounted on /run/media or /media are treated as removable. This is Linux's current and previous default locations for external media.
On Windows: External drives show up as additional drive letters and can be selected like local drives.
On Mac: In the Backup tab, enable the Show All Files control. When this is enabled, you'll be able to go to the very top (root level) of the file system and see /Volumes. External hard drives will be available for selection from there.
On Linux: External drives show up on the directory tree where they are mounted in the filesystem, typically under /run/media.
If the external drive does not appear immediately, please wait a few moments, or close and reopen the application. When the application reopens, the external drive should appear.