Some surprises are documented (some might say disclaimed) at Help Desk > Backblaze Personal Backup > How It Works and it partly reflects a philosophical difference. Backblaze does a leisurely backup, even more so for large files. Duplicati backs up as fast as it can at the scheduled time. Total disk loss can be a pain for Duplicati due to need for recreating the database before one gets totally back up. Internet speed is a factor. Backblaze can restore by mail. Different backups have different strengths. Hybrid may help, plus it’s safer…
CrashPlan is good at finding changes fast via change notifications, and Duplicati has added this (in canary):
C:\Program Files\Duplicati 2>duplicati.commandline.exe help usn-policy
--usn-policy (Enumeration): Controls the use of NTFS Update Sequence Numbers
This setting controls the usage of NTFS USN numbers, which allows
Duplicati to obtain a list of files and folders much faster. If this is
set to "off", Duplicati will not attempt to use USN. Setting this to
"auto" makes Duplicati attempt to use USN, and fail silently if that was
not allowed or supported. A setting of "on" will also make Duplicati
attempt to use USN, but will produce a warning message in the log if it
fails. Setting it to "required" will make Duplicati abort the backup if
the USN usage fails. This feature is only supported on Windows and
requires administrative privileges.
* values: Auto, On, Off, Required
* default value: off
C:\Program Files\Duplicati 2>
If one winds up backing up some area intensively, one can also set a custom retention rule to thin things out.