The header is the result of bad experiences attempting to use USB3 memory sticks.
The library here is very large with over 15,000 albums, most 16/44 in FLAC format and few hi-rez files. Backups direct to a USB3 memory stick plugged into a PC port start off well but then slow down significantly as the backup progresses. Two completely different USB3 setups have behaved in similar ways - (i) a Patriot 128GB Supersonic Rage Series USB 3.0 Flash Drive With Up To 180MB/sec- PEF128GSRUSB and
(ii) a 64GB SanDisk microSDXC chip rated at speeds up to 48 mb/s set in an ANKOR card reader.
[Of passing interest is that (ii) was faster than (i) indicating that the nominal “speed” capability of data transfer is no indication about its effectiveness in the Roon backup situation. (ii) took 1 hour 20 minutes while I have never sucessfully made a backup with (i) despite hours of impatience]
The reason appears to be that these devices are not designed to cope with the rapid read/write involved in backing up Roon, something which generates over 111,000 files in this system although the total space used by the backup is only 5.17GB.
The simple answer is to direct backups to a folder in one of the HDDs in the PC. Doing that the backup here ran smoothly without hestitation and was completed in 18 minutes.
One potential problem with this is that any backup which resides in the main PC is vulnerable to virus attacks which can catch the user despite all due care and attention with protective software. The low life that gets pleasure from destroying our data or the criminals using ransomware are often a jump ahead of that protective software so the user can never be sure of 100% protection. I got caught last year with ransomware that I suspect came on board an attachment from a trusted source. It took a long time to reinstate the data from backups.
So, the answer to this is to use the USB memory stick to copy the internal backup file onto it and then have it offline to the system. Because of the large number of files generated by the backup that copying is not quick but does not tie up Roon or other resources so can chugg away in the background and its slow speed is of no concern.
Note that the above procedure complies with the recommendation to have more than one backup source.