In the case of a restore where the backups were done from the global zone, the global administrator can reinstall the affected zones and then restore that zone's files. Note that this assumes the following:
The zone being restored has the same configuration as it did when the backup was done.
The global zone has not been upgraded or patched between the time when the backup was done and the time when the zone is restored.
Otherwise, the restore could overwrite some files that should be merged by hand.
For example, you might need to merge files by hand if a global zone has been patched after the backup, but prior to the restore of the non-global zone. In this case, you would have to be careful when restoring a zone's files that were backed up since a backed up file might not be compatible with the newly installed zone that was built after the patches were applied to the global zone. In this case, you would have to examine the files individually and compare them to the copies in the newly installed zone. In most cases, you will find that the file can be copied directly in, but in some cases, you must merge the changes originally made to the file into the newly installed or patched copy in the zone.
If all file systems in the global zone are lost, restoring everything in the global zone restores the non-global zones as well, as long as the respective root file systems of the non-global zones were included in the backup.