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NetEx Claims Broadest Storage Support

One of the  more interesting areas in data storage are de-duplication when writing to physical media and when sending data over the WAN. In the former case, de-duplication maximizes physical media. In the latter, de-duplication vastly reduces the data transferred over a relatively slow WAN connection.  In a move to garner more market share, storage vendors like IBM, with their ProtecTIER product line, offer de-duplication and replication for disaster recovery. But deduplication alone isn't always enough to improve network speeds. Optimizing the underlying transport protocols can have a profound effect on WAN replication.

NetEX's announcement about supporting more storage and replication vendors on their HyperIP  for VMware product line is a move in oneupmanship. There is something to be said for putting WAN optimization functions into virtual appliances. Doing so allows WAN optimization to be used in environments otherwise inaccessible, such as a cloud service, and is a low cost option to purchasing more appliances.

NetEx is not alone in deploying virtual appliances. Expand Networks announced their Virtual Appliance in February, 2009 and, Citrix has a technical preview of their virtual NetScalar product, VPX. Both Citrix and Expands products perform many of the functions that NetEx does, like primarily compression and TCP optimizations, which can can reduce the data transferred over the WAN as well as make better use of the WAN by removing the capacity restrictions inherent in most TCP stacks due to window sizes and acknowledgement requirements. However, both Citrix and Expand offer network de-duplication, which can have a significant effect on utilization and throughput.

Being focused on the storage industry, NetEx's products don't perform de-duplication themselves, assuming the storage system will do so. While storage de-duplication is hot, it's not a given. Even where de-duplication is in place, WAN optimization with network de-duplication may improve performance even more. Executives from Silver-Peak said in an interview some months back, that their NX appliance can further squeeze already de-duplicated data for WAN transfer.

Whether you de-duplicate in the storage process or over the network, you have a number of choices to make in maximizing WAN replication:

  • If you're bandwidth constrained, de-duplication prior to replication will reduce utilization and many make the extra network capacity available for data transfer;
  • If your network is a long, fat pipe--meaning lots of latency end to end--then optimizing the transport protocol will have a dramatic effect in performance;
  • If your WAN network suffers packet loss from 2-8%, approximately, look into error correcting protocols like Forward Error Correction (FEC), which can re-build lost packets without requiring a resend.