>From what I've read about the replication, in UD, it can replicate
across servers and when one goes down the remaining one will assume it
is now the master and continue processing transactions.  When the downed
server is restored it will be updated with the missed transactions or
rebuild the database depending on how bad the failure was.  The problem
with this idea is that over a wan you can have a connection failure and
both or multiple servers will think they are the master server and begin
processing the transactions.  They keep log files but I don't see any
way to reconcile the differences.  It also looks like there should only
be one master server at a time.  I don't think you can have 20 offices
with their own server.  

I would still look for some 3rd party solution to keep the data in sync
and have a recovery plan that would allow a merge and audit of the logs
to keep your integrity. 

Program triggers that keep all the databases updated virtually in real
time sounds like the best real world solution to me.  


Jeffrey Lettau
ERP Systems Manager
polkaudio

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jerry Banker
Sent: Thursday, September 02, 2004 2:09 PM
To: [EMAIL PROTECTED]
Subject: Re: [U2] Anyone have experience "mirroring" a HDD over a WAN

Have you looked into data replication?

----- Original Message ----- 
From: "Dennis Bartlett" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, September 02, 2004 8:19 AM
Subject: [U2] Anyone have experience "mirroring" a HDD over a WAN


Anyone have experience "mirroring" a HDD over a WAN?

We have a scenario where triggers were going to be the "data collection"
                              and
a "distribution" program to blow extracted data to various end of the
earth.

All this was an attempt to maintain a 24/7 access to a working system.
    = All log on to the main server and work as at present.
    = When comms break at any branch, they log into their own server and
      continue to work (the data being an exact copy of that on the HO
      server up until the night before
    = synchronization to take place at night, when network traffic is
lowest)


We've now had to abandon triggers, moving to a scenario where we get to
modify source code (not a preferred route). This has caused us to stop
and think... if this can go wrong, how much more the distribution of
data onto every server at every branch (20 branches, plus HO).

An alternative solution is to set up a hardware mirror to handle the
movement of data. A google produces an overwhelming array of choices...

What does the collective authority of the list say?


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