[Borgbackup] Newbie Questions

[Joseph Hesse]

Thank you for answering my previous question.

I am just learning how to use borgbackup.  I was not clear in my 
previous post as to how I am using borgbackup.  I own 2 identical 
laptops with the same OS, Fedora 31, and the same files in my home 
directory.  I need 2 laptops since I travel with them and there is the 
possibility that one of them dies due to a hardware malfunction.

I do my work on PC1 and borgbackup PC1 to an external drive.  I run, 
from a script, borgbackup when I am finished working on PC1. There is no 
point in making it a cron job.

In order to synchronize my home directory on PC1 with home on PC2, I 
plug the external drive into PC2, "borg mount" to /tmp/borg and then use 
rsync from the mounted directory to my real home directory on PC2.

Since I travel to dangerous places there is also the possibility that 
both laptops and the external drive are stolen.  Before any travelling, 
I plan to use borgbackup with the cloud service rsync.net  If anything 
happens I will buy a new laptop and use the cloud service to restore the 
new laptop.

I have 2 questions.

1.  When I set up the borg respository on my external drive I used "$ 
borg init --encryption=keyfile  localrepo"  The borg documentation says 
I should back up my key.  However, I just installed borgbackup on PC2 
and was able to read my data without ever being asked for a key, just 
the passphrase.  When I use borg on the cloud, how should I do "borg 
init --encryption=??? user at hostname:backup"?

2.  I am comfortable with computer science data structures.  I do not 
understand the "chunking" that is used in "borg create". Please, if you 
can, point me to some documentation that explains this in some detail.

I appreciate your help.  Thank you.

Joe