Earlier, we discussed how synchronous mirroring fits into our solution for high-availability. We spoke of an upper limit near 100 kilometers between mirrored nodes before round-trip latencies make lockstep replication impractical today. In other words, if you tried to synchronously mirror at longer distances, applications might time out waiting for the acknowledgement to come back from the remote end.
DataCore’s remote replication function, addresses requirements for secondary copies to be housed beyond the reach of synchronous mirroring, as in distant disaster recovery sites.It relies on a basic IP connection between locations and works in both directions. That is, each site can act as the disaster recovery facility for the other.
The software operates asynchronously, meaning that it does not hold up the application waiting on confirmation from the remote end that the update has been stored in both places. Instead, it offers to do its best to keep up to date with changes at the local site, but makes no guarantees. It’s far better than trying to constantly make backup tapes and ship them to a safe house or paying extra for point-products to handle only this task.Replication may involve multiple remote sites. For example, certain virtual disks at Site A can be copied to site B and others to Site C. Similarly, multiple remote sites may rely on the same central site as their consolidated location for replicated backup copies.