RE: Exchange Server Redundancy

  • From: "Mulnick, Al" <Al.Mulnick@xxxxxxxxxx>
  • To: "'[ExchangeList]'" <exchangelist@xxxxxxxxxxxxx>
  • Date: Mon, 8 Mar 2004 17:52:35 -0500

Tiago, is that something that you use and have seen?  How many users does
that scale to?  


From: Tiago de Aviz [mailto:Tiago@xxxxxxxxxxxxxxx] 
Sent: Monday, March 08, 2004 5:55 PM
To: [ExchangeList]
Subject: [exchangelist] RE: Exchange Server Redundancy

Jeez, what a complicated talk.


hey Jason, if you want simple replication of your Exchange server, check out
CA's BrightStor High Availability Manager at <>


It won't kill your budget ;) no need for shared storage or anything else.
Just get a spare server or another server in your network, install exchange
there and install Ca's BHB, and let it replicate. When the secondary server
detects a failure from the primary, it'll stand-in in a matter of 6 seconds
or less with the same name and IP Address.


Tiago de Aviz


(41) 340-2363 <> 


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From: Mulnick, Al [mailto:Al.Mulnick@xxxxxxxxxx] 
Sent: segunda-feira, 8 de março de 2004 18:16
To: [ExchangeList]
Subject: [exchangelist] RE: Exchange Server Redundancy

Microsoft implements "shared" clustering meaning that hardware resources
share hardware.  This is a high-availability solution and not a
fault-tolerant solution mostly aimed at reducing hardware and upgrade
downtimes (upgrades as in service packs, hotfixes, etc).  Implementing an
a/a/p cluster could certainly allow for a lot less downtime, but at a
significant cost in terms of hardware/software licenses as you've noticed.
5x9 availability requires so much more than just the software and hardware
it runs on, so I won't get into that in this thread.  Suffice it to say that
5x9's availability is a team effort that encompasses 8 layers of the OSI
model ;-)


I for one would like to see the public folder replication scheme go away.
But for fun, let's assume that Microsoft did do that.  What would that mean
in terms of availability that you can't get today?  A public folder
replication interval is 15 minutes.  Cluster failover is ~ 10 minutes or
less depending on implementation.  I'll take clustering over the public
folder replication :)


There are software products out there that claim to be able to cluster the
servers geographically and provide nearer to instantaneous failover.  I
haven't seen them myself, and can't vouch for them, but I have a hard time
understanding how they could be faster than a hardware failover and are
certainly going to add cost.  


I think that understanding what the managers really want would be helpful.
Do they want fault tolerance, or just highly available messaging service?
If the latter, do they want to have the data that's in there all the time,
or would they prefer the service to the data if it came to it?  Exchange
does have the ability to offer "dial-tone" (although I've seen some flaky
dial-tone so understand that Exchange can do better) service whereby if a
store fails, you can wipe the store, restore service in the amount of time
it takes to wipe the store and mount a new one with the same information,
and then put the data back over time using the RSG option.  It's possible
and can work for a lot of people.  VSS is another option that may be of
interest to them.  Sounds like hardware failure is the most concern, and
clustering is really a good option for that.  Gives a hot-standby host that
automatically fails over in case of hardware failure reducing the time to
heartbeat notification + time to bring the other node online or about 10
minutes depending on how implemented. 


Just my thoughts.  Glad you got it worked out.




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