We are connecting 2 Hewlett Packard XP1000 storage arrays across sites that are 33 miles apart, with "synchronous" replication
. We are planning to connect the sites using a megastream ethernet
network that has a latency of 14 millisec. We are unsure if the megastream ethernet will work for synchronous replication. As an option, we are considering a wavestream network whose latency is 2 millisec. Could you please advise which type of network connectivity will work in our scenario?
Talk with your HP representative to see how they support the XP1000 in synchronous mode with a 14 millisecond latency delay for your specific environment. In general, lower latencies are better particularly for synchronous
data communications, so a DWDM based solution such as the BT Wavestream or those from other network service provider
enable low latency with a side benefit of being good effective over-all utilization. The question of which to use will come down to what type of network service you can get for your locations, what is supported by HP and what you can afford.
Also consider if the service is protected (redundant) or if you have to buy extra redundancy separately as well as determine what the divergent network paths are. Finally have your network or prospective network provider give you a measured report of the latency between locations along with db loss. You can learn more about long distance and extended distance storage connectivity in the SearchStorage tip "Bridging The Gap", as well as chapter 6 "Metro and Wide Area Storage Networking" in my book "Resilient Storage Networks" (Elsevier).
03 Jan 2007