@Mike-B Hello again.
Re:
Not much, only that Rockstor is a btrfs only. The Web-UI only knows of btrfs and then in a slightly limited scope in order to help make the underlying magic a little more accessible.
To transfere files to and from the resulting NAS one uses the network predominantly. However it is entirely possible to do a local copy as underlying our bit is a generic JeOS like openSUSE Leap 15.2/15.2 appliance. So once can use the command line to mount and copy from all filesystems supported by that that base OS. Essentially all linux supported filesystems.
We have had a major re-write of the docs recently curtousy of @Flox and to a lesser extend myself. Likely we have a bug here somewhere.
Take a look at the following section re accessing a Rockstor share (btrfs subvolume) exported via samba:
https://rockstor.com/docs/interface/storage/file_sharing/samba_ops.html#samba
And let us know the location of the potentially miss-leading doc section you mention.
Note that many folks on the forum have done locally attached transfers but it does involve a linux command line and mount knowledge as we just don’t support that from the Web-UI.
And of particular interest is @Tex1954 recent post here:
Where they cunningly use a ye olde style file manager Midnight commander, a clone of early dos based norton commander, to lighten the load once they have already extablished the command line mount of the local non Rockstor native external media. Just be sure to create your target Rockstor shares first as they gen get their respective mount points under /mnt2/.
Hope that helps, and do take care when using the command line as there be dragons, most especially as the ‘root’ user. But if you are just connection via samba over the network then all is way more tame.