COW filesystems like BTRFS/ZFS with btrbk/sanoid are great for this. Only the initial copy may take a while, but after that it only takes the delta between the source and the destination to synchronize. On my main Server I have the OS on a single drive with BTRFS and all the actual data lives on a 4 disk zpool in raidz2. I have cron jobs set up to do hourly snapshots on both and I keep about a week worth of history. The BTRFS one gets synced to an external drive every 24 hours, while the zpool gets synced to another external 4 disk zpool on a weekly basis.
COW filesystems like BTRFS/ZFS with btrbk/sanoid are great for this. Only the initial copy may take a while, but after that it only takes the delta between the source and the destination to synchronize. On my main Server I have the OS on a single drive with BTRFS and all the actual data lives on a 4 disk zpool in raidz2. I have cron jobs set up to do hourly snapshots on both and I keep about a week worth of history. The BTRFS one gets synced to an external drive every 24 hours, while the zpool gets synced to another external 4 disk zpool on a weekly basis.