Backup and FileSnaps

A full backup of a VxFS file system that has shared blocks may require as much space in the target as the number of total logical references to the physical blocks in the source file system. For example, if you have a 20 GB file from which one thousand FileSnaps were created, the total number of logical block references is approximately 20 TB. While the VxFS file system only requires a little over 20 GB of physical blocks to store the file and the file's one thousand snapshots, the file system requires over 20 TB of space on the backup target to back up the file system, assuming the backup target does not have deduplication support.