true image restore&synthetic backup
what is True Image Restore and what is the use of it? what the relation between true image restore and synthetic backup
Google search would help you find a definition - this previous forum post has a good summary: https://www-secure.symantec.com/connect/forums/true-image-restores-whats-point
The TIR information is only taken at the start of either Differential or Cumulative backups.
The process involves taking a "snapshot" of which files are where in the volume being backed up. Using this information NetBackup can know which files have been removed (or moved) since the previous backup.
TIR information is used during the restores. If you perform a TIR restore, NetBackup will only restore files that were in the file system at the time of the last TIR backup. If a normal restore is done, all files are restored even if they were deleted between the time of the full and following incrementals.
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For Synthetic Backups, you must have TIR enabled.
See this technote
True image restore and synthesized backups
http://www.veritas.com/docs/000079451