Product : DataCore, SSY [SDS]/10.0 PSP12, x86
Feature : SC Distance, Disaster Recovery, Data Availability
Content Owner:  Herman Rutten
RTT = Round Trip Time

In truth the user/app with the least tolerated write latency defines the acceptable RTT or distance. In practice <5 ms RTT is targeted. The maximum tolerated RTT by DataCore SANsymphony is 30 seconds per write IO.