Increasing the storage capacity of a Data Domain is usually a matter of adding an additional disk shelf to the Data Domain head. Upon connecting the additional enclosure your new disks will be in an Unknown state. This does not necessarily mean there’s anything wrong with the topology of the system, but just indicates the disks aren’t in use just yet. This is however easily fixed with a couple of CLI commands.
Last week I’ve been implementing two new Data Domain systems for a new customer who’d like to use these systems as backup targets for their existing Veeam 8 environment. Backup would be replicated to the secondary system to guarantee recoverability even if the first system or data center experiences a catastrophic failure. In this case replication will be handled by the Data Domain system itself. You’d like your backup software to be aware of the replicas on the secondary location. This in turn means Veeam should be able to read from the replica, which turned out to be a bit of a configuration challenge. Bring out the CLI!