We are using a half-hourly VOB synchronisation schedule.
Taking a simple example of four sites (A, B, C & D) synchronising a single VOB with the original at site A, we are using the default for sync_export_list schedule (i.e. -all) which exports packets to all site replicas (for all VOBs).
So, how does sync_export_list -all work?
I understand that a single packet exported from A will be exported to B, C & D. So, assuming there have been no other changes at sites B, C or D during this short window, my epoch matrix for this VOB will be up-to-date. However, am I correct in thinking that the epoch matrix at B will show C and D as out-of-date, and will therefore needlessly re-export the same packet content to C & D (assuming sync_export_list -all at site B also)? Or do the original packets from A to B, C & D indicate that the packets have been sent to the other sites and so they will be up-to-date on receipt of this first packet without sending/awaiting the "echo" packet between the other sites? (I wish!)
Otherwise, how can we avoid redundant "echo" packets and ensure that the VOB replicas are up-to-date? And would this work okay if changes were permitted on both sites simultaneously?
Alternatively, is it better to use a hub solution? Is there a problem if site A (as the original) acts as the hub for this VOB, and exports to -all other sites, but the other (subsidiary) sites simply export their own replica changes to the (master) hub replica only.
Alan Dougall
alan.dougall@roke.co.uk
+44 (0)1794 83 3787
Roke Manor Research Ltd, UK
A Siemens Company
This archive was generated by hypermail 2b29 : Tue Jul 31 2001 - 22:03:56 EDT