When considering using Replication to move or backup data from remote locations, available bandwidth, as well as tolerance to a range of varying network conditions, must be considered. Remote locations frequently have varying bandwidth availability that needs to be shared among multiple applications and users. For this reason, remote data management and movement solutions should have features that enable efficient use of available bandwidth such as byte-level differential data transfer, bandwidth throttling, multi-streaming and compression. Having a fairly “skinny” network pipe can be a critical issue. To put this in perspective:

With a 384Kb network pipe, passing 1GB of data would take six hours and two minutes.
With a 1.5Mb T1 network pipe, passing 1GB of data would take one hour and 33 minutes.

Understanding the rate of data change in between backup periods is also key. A typical rate of change in a “fairly busy” remote office typically ranges between .5% to <% can be considered small to moderate rate of change; 5% per day is considered a heavy rate of change.

Best case scenario: 500MB daily x 5% = 25MB/day VERY do-able with either network pipe.
Worst case scenario: 50GB daily x 5% = 2.5GB/day do-able with a T1 (~3hours), but not with a 384Kb network pipe

Note: BOTH of these scenarios vary greatly with: compression, encryption, byte-level changes only, and bandwidth throttling levels.

In addition to data rates, the amount of network overhead (or information) needed is also an important consideration (with less being better). Finally, since some remote connections will likely be impaired during some processes, the ability to restart at the point of failure is critical as well as the ability to re-route information flow to alternate networks.

SR…

This entry was posted on Sunday, October 16th, 2005 and is filed under Storage Applications, Advisor - Steve. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.