This article is a summary of the Data Domain (DD) system supported protocols, and also explains the configuration about on a single DD platform using these protocols in order to help the readers to consolidate the basic concepts.

DD supports five protocols:

1. NFS - the file system of DD is made ​​NFS share to UNIX client, over TCP / IP (shown in Figure 1).

2. CIFS - the file system of DD is made ​​CIFS share to Windows client, over TCP / IP (shown in Figure 1).

3. DD Boost - OST protocol developed base on Symantec, allows backup software through the HBA iSCSI port on the backup server to access the storage space on DD (disk format), over TCP / IP (shown in Figure 1).

4. NDMP - need to build VTL, allows backup software to back up data on the NAS devices to the storage space on DD (tape format), over TCP / IP (shown in Figure 1).

Figure 1

5. VTL - simulate the DD file system into a tape library, so that the backup software through the HBA FC port on the backup server access the storage space on DD (tape format), over FC (shown in Figure 2).

Figure 2

While Data Domain systems support both the VTL and DDBoost protocols (running simultaneously on one system), there can be a performance and capacity issue in the implementation. It is important to carefully consider capacity (if VTL is also used as a primary target for backup), as there is no quota facility to allocate space between the two protocols.

Space reclamation does not happen automatically for VTL. Even if the catalog/index is expired from the backup application, the disk space will not be reclaimed even if you run Garbage Collection (for example: GC or Cleaning). The backup administrator needs to re-label the volume or erase the tape volume. When this process is complete, our GC will then be able to clean up and reclaim the space.

The behavior is different with DDBOOST. If the catalog/index is expired from the backup application, there is an automatic clean-up process that occurs within the backup application. For example with NetBackup, there is an image clean process that automatically runs when the catalog is expired. When the GC process runs, space will be reclaimed. 

Author:Kevin Liu

             

iEMC APJ

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