RE: Exchange Server Redundancy
- From: "Tiago de Aviz" <Tiago@xxxxxxxxxxxxxxx>
- To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
- Date: Mon, 8 Mar 2004 20:06:13 -0300
Sure, i'm using it right now. I also have many customers using it for
replication of SQL Server databases, Oracle databases, IIS web servers, file
servers... It's an outstanding product. It's based on the ARCserve technology,
but it basically does replication tasks from one server to the another in
real-time, and runs scripts that are built-in in the application in the case of
a failure.
It requires a special communication link between the two server (get yourself
two nics and a crossover cable), and it detects failures when the service on
the two machines can't talk to each other anymore. When it detects this
failure, it starts pinging addresses that you specify to ensure it is online,
or it can verify if the primary server is still alive via the COM port.
Primary server dead? It starts the Brightstor service, and the secondary server
starts answering as the primary, and noone notices what happened.
Well, it can scale to as much users as you want, it basically depends on your
hardware. All it does is database replication, Al. It doesn't know how many
users you have when it's replicating. It's just replicating the .edb file and
that's it. When the primary server crashes, it'll bring the exchange server up.
We always recommend having the same hardware on the primary and secondary
servers, to simplify things. But yes, you can have totally different machines
for this service.
Tiago de Aviz
SoftSell
(41) 340-2363
www.softsell.com.br <http://www.softsell.com.br/>
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_____
From: Mulnick, Al [mailto:Al.Mulnick@xxxxxxxxxx]
Sent: segunda-feira, 8 de março de 2004 19:53
To: [ExchangeList]
Subject: [exchangelist] RE: Exchange Server Redundancy
http://www.MSExchange.org/
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
http://www.MSExchange.org/
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 www.ca.com <http://www.ca.com/>
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
SoftSell
(41) 340-2363
www.softsell.com.br <http://www.softsell.com.br/>
Esta mensagem, incluindo seus anexos, tem caráter confidencial e seu conteúdo é
restrito ao destinatário da mensagem. Caso você tenha recebido esta mensagem
por engano, queira por favor retorná-la ao destinatário e apagá-la de seus
arquivos. Qualquer uso não autorizado, replicação ou disseminação desta
mensagem ou parte dela é expressamente proibido. A SoftSell não é responsável
pelo conteúdo ou a veracidade desta informação.
_____
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
http://www.MSExchange.org/
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.
Al
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