When it comes to disaster recovery, there has historically been a limitation on disk storage. While tapes can easily be sent offsite to be used for restores after a site outage, disks do not offer the same flexibility.
Some OpenStorage technologies, support out-of-band replication in which the contents of the disk storage are replicated between devices. In these instances, NetBackup has no knowledge of the data, which complicates recovery in a NetBackup protected environment because the replicated data can only be accessed after recreating the NetBackup catalog. Replication is done by importing the entire contents of the disk storage at the remote site using the bpimport command. The nbcatsync utility, introduced in NetBackup 6.5.6 and 7.0.1, can address this challenge as well, but it relies on being able to restore the catalog from a catalog backup and then post-processing it to reconcile the disk device mappings, resulting in a very time consuming process.