[Spread-users] WAN usage

John Robinson jr at vertica.com
Thu Nov 15 17:14:42 EST 2007

I know this comes up on the list from time to time, and now it is my 
turn to query.

I did a brief experiment (then lost the machines) where a real WAN 
intervened between two local segments (same machine room) and one remote 
segment (hosted machine elsewhere).  Connectivity between segments used 
a VPN arrangement so all ports could go through without need of firewalls.

The daemons all came up and found each other fine, but the remote one 
would wink out every couple of minutes (membership change messages 
etc.).  The attached client processes were not sending any traffic 
except a few brief messages to track their own group status in response 
to spread's membership change messages.

I did not have a chance to try bandwidth checks with the set-up.  Is 
there any good rule-of-thumb for what bandwidth, latency and delivery 
probability guarantees the spread daemons need to stay connected?  Do I 
need to spmonitor the setup?  I am perfectly willing to believe that the 
service I was receiving in my setup was atrocious.

Also, I had set broadcast addresses on the segments with 1 machine per 
segment.  I now know that this broadcasts needlessly on the segments but 
aside from that should there be any ill effect on the inter-segment packets?

I hope to get to experiment more with the setup over the next few 

Many thanks,

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