The registry database is stored in files. In Windows 2003/NT/2000/XP, most of the registry is stored in files in \Winnt\system32\config-directory, user parts are in user directories. These registry files are also called REGISTRY HIVES. For example HKEY_LOCAL_MACHINE\SAM-tree is stored in \Winnt\system32\config\SAM.
If a registry hive file is to be backed up, Stratesave asks Windows to dump the hive contents from the registry database to a new file. This dump file is then backed up under the name of the hive file.
Often the dumped file is smaller than the hive file, because empty database stuff is removed in the process. That's where the messages 'Size of backed up registry file differs from real file' are coming from.
Every registry hive (part of the registry) is stored in two files: Primary hive file ( for example SAM) and temporary hive file (e.g. SAM.LOG). The temporary hive file is only used while the hive is loaded (active), for temporary updates. When rebooting, everything is stored in the primary hive file. Only the primary hive file needs to be backed up. In fact, when the registry is dumped, only one hive file (the primary) is created and this one is backed up. The backed up SAM-file is a registry dump, and contains all information stored in primary and temporary hive files SAM and SAM.LOG. That's where the messages '... not backed up: Temporary registry file' are coming from.
See also: How Stratesave restores the Registry
How Stratesave backups up the System State
Network backup with Stratesave