Performance of a cluster depends on the latency and bandwidth of
the interconnect. At least dual 1Gbit ethernet is recommended for
each node. Thus a cluster should be on a single local or system
If regional copies are needed, we would replicate between
clusters by asynchronous log shipping. This requires some custom
When a transaction is committed at one site, it is logged and
sent to the subscribing sites if they are online. If there is no
connection, the subscribing sites will get the data from the log.
This scheme now works between single Virtuoso servers, and needs
some custom development to be adapted to clusters.
If replicating all the data of one site to another site is not
possible, then application logic should be involved. Also, if
consolidated queries should be made against large,
geographically-separated clusters, then it is best to query them
separately and merge the results in the application. All depends on
the application level rules on where data resides.