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Multi-spanning gets activated directly in Z-DBackup!
Z-TapeBackup was developed mainly as a module for Z-DBackup to allow backups configured in Z-DBackup to be copied onto tape. This is why some backup functionality is only available in Z-DBackup and not in the standalone version of Z-TapeBackup (e.g. multi-spanning and sending emails)
To use multi-spanning you have to setup a backup set and activate the option in Z-DBackup.
Multi spanning (with the Z TapeLoader)
With multi spanning, the files to be backed up are written across several tapes. The number of empty tapes needed is calculated at the start of the backup. Z TapeBackup assumes that 96% of the native tape capacity can be used for data. This value (usable tape capacity) can be changed in the Z TapeBackup settings.
The native tape capacity is the capacity of the tape without hardware compression. The remaining part, by default 4%, is used by Z TapeBackup for file information and tape marks. It is also used as a buffer in case there are bad blocks on the tape.
Bad blocks are areas on the tape that can no longer be used to store data. The number of bad blocks increases over time, depending on how often the tape is used. A bad block is only detected when Z TapeBackup tries to write data to this part of the tape. Because of this, Z TapeBackup cannot know in advance how many bad blocks a tape has or how much data will really fit on it. The default value of 96% is only an estimate. If, during the backup, it turns out that not all planned files fit on the tape because of too many bad blocks, the backup will fail. In this case you should lower the usable tape capacity value in the Z TapeBackup settings.
Even if you enter your tapes in the configuration with double capacity, Z TapeBackup internally always uses the real native capacity of the tape. This makes the calculations for multi spanning and the reserve for administration data reliable.
For multi spanning you should use tapes with the same native capacity. Up to 48 tapes can be used. Single files cannot be split across multiple tapes. The largest file must not be larger than the capacity of one tape.
If you want to use multi spanning with a tape library and the Z TapeLoader, you must select the first tape for the backup in the settings (slot 1 to 41). If this setting is missing, automatic multi spanning in the library cannot be used and you have to change the tapes by hand during the backup. This is not recommended.
Manual multi spanning is not possible if the tape backup is started by a schedule or if Z DBackup or Z TapeBackup are running as a service, because in this case the tape change would have to be done manually.
After you have set up multi spanning, you should test your settings with the preview function. The complete backup run is simulated, but no data is written to tape. This lets you check if your settings are correct before the real backup runs. You can view the result of the preview in the Z DBackup log file and adjust your settings if necessary.
Program
•Main window
•Set up medium
•Data selection
•Directory selection
•Backup
•1-click backup
•Task scheduling
•Restore
•Backup view
•Logfile
•Saving methods
•Program Setup
•Commandline
•Context-sensitive help
•Online Updates
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