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Online Server Backup and The Importance of WAN Optimization

by Zetta Staff

There are two things that companies never seem to have enough of: disk space and bandwidth. Both are consistently increasing and as capacity increase, so does demand. Compounding the problem for networks is that as links become congested, throughput drops, leading to further congestion.
This is similar to the situation described in the paper The Freeway Congestion Paradox by Chao Chen and Pravin Varaiya of the PeMS Development Group of Berkeley’s Department of Electric Engineering and Computer Science.
Chen and Varaiya looked at traffic flow on a section of Interstate 10 in Los Angeles. They found that at 5:00 a.m., the fast lane was carrying 2100 vehicles per hour travelling 60 mph. At 7:00 a.m. the speed had reduced to 15 mph and the lane was only carrying 1300 vehicles per hour. In other words, although there were a lot more vehicles on the road during rush hour, congestion had dropped the actual traffic flow to just 15% of what it was two hours earlier.
“The evidence points unmistakably to the conclusion that maximum flow occurs at free flow speeds ranging from 65 mph in lane 1 to 55 mph in lane 4,” they wrote. “This means that the most efficient way to operate our freeways is to prevent congestion and to keep traffic moving freely.”

Networks see a similar situation when a line is congested. Packets get lost or delayed which leads applications to automatically retransmit the data, or users to keep hitting refresh, both of which increase the congestion and produce further delays.

A Suite of Technologies For Fast Online Server Backup Performance

WAN Optimization is a set of techniques designed to increase flow over a link and eliminate congestion within your online server backup solution. These techniques include:

  • Deduplication: Not sending multiple copies of the same data, but just transmitting a pointer that references the earlier sent data.
  • Traffic Shaping: Assigning priority to certain types of protocols or users. For example, making sure that the database access takes precedence over streaming videos.
  • Compression: A variety of methods depending on the traffic type. For example, at the file level, this can include assigning a shorter string of bits to commonly used characters. For the packets, it can mean reducing the amount of header information when a series of packets belong to the same transmission.
  • Caching: storing copies of commonly used files at the branch office or another location nearer the users to avoid multiple transmissions.
  • Rate Limits: Restricting the amount of bandwidth allocated to a user.
  • Multicasting: Sending a single copy of a transmission to multiple users. The networking gear nearer the users, say at the branch office, then creates individual copies for each recipient.

The Zetta Approach to Online Server Backup

WAN acceleration is commonly implemented as a network appliance, and while these appliances do a great job of addressing problems of network congestion, they can be thousands of dollars per unit. The appliance needs to be installed at both the source AND the endpoint of the transmission so the cost can be overwhelming. WAN optimization is primarily a matter of software. Appliances are simply one way of running that software, but it can often be achieved at the server, the switch, the router, or even an individual PC or laptop.
Zetta Data Protection uses appliance-less optimization to ensure that your backups do not overload the network. It includes data deduplication at the source to ensure that only changed blocks get transmitted over both the LAN and the WAN. The data, after deduplication, is then compressed to reduce network traffic.
At Zetta’s data centers, all data is immediately cached to SSD before writing it to disk so backups are never delayed or need to be transmitted due to not being able to write the data fast enough.The transmission itself is done using the multi-threaded WebDAV protocol, which allows simultaneous parallel transfer of up to 32 backup streams.
With Zetta’s WAN optimization technologies, customers can transfer Terabytes of backup data daily over standard Internet connections without paying a congestion penalty. (Now, if only we could deduplicate the freeways.) To see how quickly you can start backing up with Zetta, start your free trial today.

Zetta Staff
Zetta Staff

Zetta’s pioneering cloud backup and recovery technology provides the surest path from data disasters to business as usual.