I have a backup system which uses
rdiff-backup locally, then copies the backup to a remote server using
rsync. My rsync command looks like this:
rsync -aP --delete-after /mnt/reos-storage-2/data_upload_backup/ [email protected]:/mnt/reos-storage-2/data_upload_backup_ed-mh-pi01
This occasionally results in the following error, and my backup is not copied to the remote machine.
ssh_exchange_identification: Connection closed by remote host rsync: connection unexpectedly closed (0 bytes received so far) [sender] rsync error: unexplained error (code 255) at io.c(235) [sender=3.1.3]
I have investigated the
ssh_exchange_identification error and seen that it can be due to a few reasons, the main one being too many ssh connections. However, at the time this runs there should be no other ssh connections active on either machine, or maybe one or two others at most. The 'source' machine in this case is a raspberry pi running Raspian, while the 'destination' server is Ubuntu 20.04. I wondered if maybe rsync creates lots of connections?
How can I debug this? What are the possible reasons for the error?