Replication Topology 103 - End to End
Tags :Replication
Prerequisites are Replication Topology 101
(the basics) and 102
(peer to peer) before you hit
this one.
From the beginning, I gave a scenario of
how it looks
Basically data starts
on one end, passes through multiple servers through replication and then
comes right back. Timing becomes and issue to make sure that data
can make it all the way down and back before the next baton is passed.
Think of it as runners that pass the baton, and if one runner takes
off too early, who knows where the baton is.
So I hopefully already broke you away from
the idea of a meshed environment in class 101 due to the sheer number of
connection records that are possible and messy management.
End to end offers it's own set of benefits
and pitfalls, of course. If you can imagine your science class from
way back in elementary school.....where they gave you a stack of batteries
and a bunch of light bulbs. You were then told to light them all
up. The first thought is batteries, then wire to next bulb, then
wire to next bulb and so on until they were all connected. Well if
one went out in that serial connection idea, then everyone behind them
went out. So the teacher taught you about parallel connectivity to
get around it. Which end to end does not do in the true form. Any
variation moves it towards circular or even tiered architecture (with a
bizarre slope).
The benefit is that data passes along in
a cycle, reducing replication conflicts. Save conflicts are entirely
different as people across the string could be editing the exact document
on every server. Timing, as I mentioned, also becomes and issue since
it could run any amount of time to get the data back and forth. If
a server or network is down, the others will replicate as scheduled, yet
that missing link in the middle brings the idea of timeliness to a screeching
halt on each end.
The end result is a long line of servers,
spread in the same room or geographically, that have a start and end point.
Sure, you can argue that every topology has a start and end point.
But with the proper hub cluster setup, only an individual spoke failure
would affect any users. In end to end design, there are too many
holes along the way.
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On Tuesday, August 16th, 2005 by Chris Miller
