"Dirvish makes snapshot copies of changed files. So the cron job that runs at 00:30 each night copies changes in files in the 8 vaults (directories or partitions). What I want to follow that daily update is to copy only the changed files from bkup1 to bkup2."
So, you're using a disk imaging tool to create incremental backups and the using a remote file synchronization tool to do another incremental backup. Why not just use 1 tool such as rdiff-backup? It's simpler and it has more useful backup & recover features. "Rdiff-backup backs up one directory to another, possibly over a network. The target directory ends up a copy of the source directory, but extra reverse diffs are stored in a special subdirectory of that target directory, so you can still recover files lost some time ago. The idea is to combine the best features of a mirror and an incremental backup. Rdiff-backup also preserves subdirectories, hard links, dev files, permissions, uid/gid ownership (if it is running as root), modification times, acls, eas, resource forks, etc. Finally, rdiff-backup can operate in a bandwidth efficient manner over a pipe, like rsync. Thus you can use rdiff-backup and ssh to securely back a hard drive up to a remote location, and only the differences will be transmitted." https://rdiff-backup.net/
