The following topics cover the use of Backup Agent:

Continuous Operations is a MicroKernel feature included with Zen that provides you the ability to put data files in a temporary state so that you may backup data files while the database files are open and in use.

During a backup, open data files are typically omitted because they are open and in use. When turned on, Continuous Operations calls to the MicroKernel to open the selected files as Read-Only. Doing this allows the backup utilities to access and backup a static image of the selected files. Once the data files are open as Read-Only, the MicroKernel begins to record any changes made to the files in temporary delta files. These temporary delta files retain running versions of the files, complete with the changes that have transpired during the backup process.

The temporary delta files created by Continuous Operations mode have the same name as the corresponding data files but use the extension ".^^^" instead. No two files can share the same file name and differ only in their file name extension if both files are in the same directory. For example, do not use a naming scheme such as INVOICE.HDR and INVOICE.DET for your data files.

In the case of same name files, only one file will be placed in Continuous Operations. The Backup Agent log file will detail the file that is excluded from Continuous Operations. If all files are intended to be placed in Continuous Operations, review the log file and either place same name files in different directories or consider renaming files so that all are placed in Continuous Operations by Backup Agent.

After the backup is complete, the data files must be removed from Continuous Operations, at which time the changes stored in the delta files are rolled into the data files. The MicroKernel then deletes the delta files as soon as all changes are rolled into the data files.

Starting Continuous Operations mode is handled in Zen through butil or the Maintenance utility, depending on the type of files you are accessing. The Maintenance utility is the interactive version of butil and requires file paths.

Ending Continuous Operations is also handled in Zen through butil or the Maintenance utility, depending on the type of files you are accessing. The utility you used to invoke Continuous Operations is the same utility you would use to end Continuous Operations.

Advanced Operations Guide provides in-depth information on the Continuous Operations functionality provided in Zen.

So why would you use Backup Agent if you already have the utilities available to start and end Continuous Operations for backing up Zen databases? Because Backup Agent takes Continuous Operations a step farther. Backup Agent implements what we call intelligent Continuous Operations management.

With intelligent Continuous Operations management, files are placed into Continuous Operations automatically by the agent instead of a system administrator providing (and maintaining) a list of files that are to be backed up. This file management eliminates the need for butil -startbu scripts that can too often get out of date. It also eliminates putting files into Continuous Operations that are not opened by users during a backup session. Backup Agent handles only the files that are accessed and that need to be put into Continuous Operations. This can reduce the amount of data that is backed up during incremental or differential backup processes drastically.

Another good reason to use Backup Agent is because it integrates quickly and easily with most popular backup software products on the market.

The next section covers some of the issues surrounding data backup and precautions you should know when using Backup Agent.

This topic lists some precautions and considerations you should be aware of before you begin using Backup Agent.

If you have enabled Archival Logging in Zen, you must disable it before you can use Backup Agent. If you are uncertain if Archival Logging has been enabled, you can check the setting in Zen Control Center to verify.

The MicroKernel locks temporary files. Consequently, Backup Agent does not place temporary files into Continuous Operations.

In the scenario where a file resides in a read-only directory, the MicroKernel is unable to create a delta file, and Backup Agent does not put the file into Continuous Operations.

Although read-only files cannot be accessed for Write operations, Backup Agent puts these files into Continuous Operations. The MicroKernel does not create the delta file, since there would be no updates to a read-only file. The MicroKernel will then return an error on any Write operation and the Write operation will be not be carried out. Since the delta file is never created, there is nothing left for Backup Agent to manage.

If your business rules dictate that you start and stop Backup Agent from a remote machine, you may do so using any of the remote access software applications available on the market. (For example, you may need to start Backup Agent using a Telnet session.)

Using BUTIL or the Maintenance Utility to start Continuous Operations is strongly discouraged. If a file is put into Continuous Operations by another utility, Backup Agent cannot manage it. It is then your responsibility to remember to take the file out of Continuous Operations, using the same utility with which you put the file into Continuous Operations.

To avoid a potential performance decline, you should always try and schedule your backup process to run during off-hours or periods of low data activity. It’s also important to be certain and stop the agent once your backup has completed. The following circumstances could impact your database application performance when running Backup Agent.

In the event that you have files in Continuous Operations using Backup Agent and the server is restarted, there is a 30 minute limit for rolling in changes. If the 30 minute timeout is reached, Backup Agent logs the file at which the timeout occurred. Any delta file still active will continue to increase in size if database changes are still being made to the original file. The delta file continues to grow until the changes are rolled in to the original file. You can eliminate this situation by opening the original file using the Function Executor or Zen Control Center to roll in the delta file.

If you are using Backup Agent with your backups and you encounter a hard drive failure, you cannot use Archival Logging and the Maintenance utility Roll Forward command to restore changes to your data files that occurred after the last backup. If a hard drive failure occurs, you will lose all changes to your data since the last backup.

If the server goes down while Backup Agent has files in Continuous Operations, Backup Agent detects the existing delta file and rolls in the changes when the server is restarted the next time.

You can specify files for Backup Agent to include in Continuous Operations by specifying the files in the inclusion file (ifl.txt). Conversely, you can specify files to be excluded from Continuous Operations by using the exclusion file (efl.txt).

If you successfully installed Backup Agent, the include (ifl.txt) and exclude (efl.txt) files are available in the following location:

If you place a file into Continuous Operations using butil or the Maintenance utility, the file is not excluded although it is listed in efl.txt.

List files separated by semicolon or by listing each file on a separate line in the include file list (ifl.txt). You can also use wildcard patterns to include files. Filenames must include the absolute pathname.

List files separated by semicolon or by listing each file on a separate line in the exclude file list (efl.txt). You can also use wildcard patterns to exclude files.

The Backup Agent command line utility pvbackup.exe is a perfect solution for integrating an automatic Continuous Operations function with your backup software applications. Before we discuss implementing this utility with a backup software application, we will first look at using the utility by itself.

You can easily implement Backup Agent into popular backup software applications. Some backup applications can be configured to have specific operations or scripts run prior to a scheduled backup. With this functionality, you may also have the flexibility built in to the software to run specific operations or scripts after a backup has completed.

For example, some backup applications allow you to set Pre or Post commands. So where you configure a Pre command, you might enter something similar to the following, depending on the specific requirements of your backup software.

You would also specify a Post command, to be executed after your backup finishes. An example of this might be something like the following, depending on your backup software requirements.

Depending on the backup software you are using, you may not need to enter the full pathname. Refer to the user documentation or online help that accompanies your backup software for specific requirements.

The Backup Agent GUI utility pvbackupgui.exe is designed as a one-touch solution for managing backup files. This utility may become your first stop to start an ad-hoc backup process.

Open the Backup Agent GUI from the operating system Start menu or Start screen or from ZenCC.

In the Backup Agent dialog, click the Help button with the question mark in the upper right corner of the dialog.