What We Don't Backup
Backblaze does not want to waste your bandwidth or Backblaze datacenter disk space. Thus, we do not backup your operating system, application files, or temporary internet files that are transient and would not be useful in the future. Backblaze also excludes podcasts in iTunes.
Certain Filetypes
You can see these exclusions by clicking on “Settings…” in the Backblaze Control Panel and selecting the Exclusions tab. They can be removed in Backblaze 2.0! Some of these excluded files are:
ISO (Disk Images)
VMC VHD VMSN (Virtual Drives)
SYS (System Configuration & Drivers)
EXE (Application Files).
Other Backup Programs
Backblaze also doesn't backup backups like Time Machine and Retrospect RDB.