DHCP checkpoint files

The syntax for the checkpoint files is not specified.

If the server crashes or you have to shut down and cannot do a normal closing of the database, the server can process the checkpoint and backup files to reconstruct a valid database. The client that is being written to the checkpoint file when the server crashes is lost. The default files are:

/etc/db_file.cr

normal database operation

/etc/db_file.crbk

backups for the database

/etc/db_file.chkpt and /etc/db_file.chkpt2

rotating checkpoint files

The DHCP server is threaded. To maintain high throughput, database operations (including save operations) are thread-efficient. When a save is requested, the existing checkpoint file is rotated to the next checkpoint file, the existing database file is copied to the backup file, and the new save file is created. Each client record is then logged and a bit is toggled to indicate that the client should use the new checkpoint file for logging. When all client records are recorded, the save is closed, and the backup and old checkpoint files are deleted. Clients can still be processed and, depending on whether the client record has been saved, database changes go into a new save file or to a new checkpoint file.