Dne 19.11.2011 03:35, Digimer napsal(a): > WAN/Stretch clustering suffers most for network latency. If you need to > keep the data in sync across both nodes, using DRBD will limit your hard > drives, effectively, to the speed and latency of the link between your > nodes at the different DCs. This is rarely usable. > > Stop by #linux-cluster and/or #drbd, I know there are folks there from > Linbit and Hestaxo who could help you, but you're going to be facing > rather expensive technical challenges. :) DRDB over WAN is nonsense. There are many scenarios expensive/non-expensive, depends on data you want to distribute. Being you I would start with the simplest one. I can name a few: - buy netapp and create metrocluster with RRDNS - have your subnet routed into both datacenters and use virtual IPs - webapp might be somewhat static, so files might be easy to sync, as to DB data, start with master-slave replica and M/S swap, try to read data from multiple source, write to only the one - you are talking about two nodes, with your scenario only one will serve the data in time, it's not horizontal scaling, try to use both in time - have low ttl for DNS with RRDNS, add/remove records by nodes' status - don't forget about webapp side of topic, webapp must be prepared to save nonDB content - start with two nodes in one dataceter to test your horizontal scenario, you can than split it into two DC or easily add the third/fourth nodes in another DC - .... DH