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Dell EMC Data Domain

DataDomain MTree overview and limits

Dell EMC defines MTrees as logical partitions of the file system and they are identified by unique names. MTrees are used to create (protocols can be mixed, except VTL):

  • DD Boost storage units
  • VTL pools
  • NFS/SMB shares

MTrees allow granular management of snapshots and quotas. Quotas apply only to logical data written to an MTree.

There is a fixed amount of MTrees that can be created on a Data Domain system and it depends by the model and DD OS version.

DataDomain system DD OS version Configurable MTrees Concurrently Active MTrees
DD9900 7.0+ 256 256
DD6900, DD9400 7.0+ 128 128
DD9800 6.0+ 256 256
DD9500 5.7+ 256 256
DD6800, DD9300 6.0+ 128 128
DD6300 6.0+ 100 32
DD2200 5.7+ 100 32

DataDomain replication overview

Data Domain Replicator is a technology that allows replication between two (or more) Data Domain systems. The replication process is network-efficient as no data re-hydrate happens when transferring data between two systems.

To reduce bandwidth usage, Data Domain Replicator performs two levels of deduplication:

  • local – determines the unique segments that must be replicated over WAN
  • cross-site – it further reduces bandwidth requirement when multiple systems are replicating to the same target (many to one architecture)

Data Domain Replicator is a licensed feature.

Replication types

Replication always involves at least two Data Domain systems, identified as source and destination and each system can be either source and destination (cross-replication). The process is always asynchronous.

A Data Domain can be set up for different kind of replication, such as:

  • Directory – replication based on single directory (the smallest entity within an MTree)
  • Collection – entire Data Domain content
  • MTree – entire MTree replication, including all subfolders

Replication considerations

Watch the load on the DataDomain systems. Replication may get stuck with lower-end DataDomains, especially when undersized and with constant high load. While the issue is acknowledged and a fix may be in the way, parallelism in this case should be avoided, as doing backup and DD replication sequentially works properly.


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