Backup copies of PREIMG files can be made using the following approaches:
Online backup using dynamic dump
Although automatic recovery is not available to PREIMG files, it is possible to perform periodic dynamic backups of PREIMG files using FairCom DB’s dynamic dump feature. Using the PREIMAGE_DUMP dynamic dump script option promotes PREIMG files to full TRNLOG files during the dynamic dump process. The promotion to a TRNLOG file means that a full transaction log is maintained during the dump process. This process guarantees that any changes made to the files during the backup are saved in these specially maintained transaction logs. The ability to dynamically back up user data files minimizes the loss of the automatic recovery feature with this mode. The dynamic dump produces a dump stream file containing the disk contents of the PREIMG files and the changes made during the dynamic dump. If it becomes necessary to restore the backup copy of the PREIMG files, the ctrdmp utility can be used to extract the PREIMG files from the dump stream file, restoring them to their state at the time of the backup.
Offline backup using file copy
An offline backup of PREIMG files can be performed using system file copy utilities when the server is shut down or when the server is running and the files to be backed up are closed. It is important to ensure that the server is shut down or the files are closed before making a backup copy of files using a system file copy utility in order to ensure that all updated buffers are flushed to disk. Otherwise, data may be lost and the file may be in an inconsistent state.