The deduplication feature has the following limitations:
A full backup of a deduplicated Veritas File System (VxFS) file system can require as much space in the target as a file system that has not been deduplicated. For example, if you have 2 TB of data that occupies 1 TB worth of disk space in the file system after deduplication, this data requires 2 TB of space on the target to back up the file system, assuming that the backup target does not do any deduplication. Similarly, when you restore such a file system, you must have 2 TB on the file system to restore the complete data. However, this freshly restored file system can be deduplicated again to regain the space savings. After a full file system restore, Symantec recommends that you remove any existing deduplication configuration using the fsdedupadm remove command and that you reconfigure deduplication using the fsdedupadm enable command.
Deduplication is limited to a volume's primary fileset.
Deduplication does not support mounted clone and snapshot mounted file system.
After you restore data from a backup, you must deduplicate the restored data to regain any space savings provided by deduplication.
If you use the cross-platform data sharing feature to convert data from one platform to another, you must remove the deduplication configuration file and database, re-enable deduplication, and restart deduplication after the conversion. The following example shows the commands that you must run, and you must run the commands in the order shown:
# /opt/VRTS/bin/fsdedupadm remove /mnt1 # /opt/VRTS/bin/fsdedupadm enable /mnt1 # /opt/VRTS/bin/fsdedupadm start /mnt1
You cannot use the FlashBackup feature of NetBackup in conjunction with the data deduplication feature, because FlashBackup does not support disk layout Version 8 and 9.