RE: Exchange Server Redundancy
- From: "Jason Merrique" <j.merrique@xxxxxxxxxxxxxxx>
- To: "[ExchangeList]" <exchangelist@xxxxxxxxxxxxx>
- Date: Mon, 8 Mar 2004 20:43:32 -0000
Hi Al,
Bit of a delay, but this is a reply to Al Mulnick and Sonny Willis
(Thanks for your input on this chaps, your expertise is very much
appreciated.)
The whole redundancy issue was brought up by management who (as always)
would like as near 100% uptime as is possible. As it happens, the
hardware failure last week only caused about 2 hours of downtime and
safeguards were put in place to insure that a repeat occurance would be
highly unlikely. My initial instinct was that it wouldn't be worth the
investment in additional hardware and licensing for the 99.999% (2 hours
in the whole year) to 100% improvement. So I'm left thinking that its
just not worth it.
So clustering and cloning may not be the answer. But I would like to
confirm - Is there really no way to replicate mailboxes between servers
using Exchange 2003? Doing this in the same fashion as Public Folders
would be excellent. Maybe allowing a simple redirection to the secondary
server if the primary falls over? Or is this just wishfull thinking on
my behalf!?
Sonny: I don't suppose you know how NeverFail copes with differences in
hardware and SIDs between the primary and secondary server? If its an
exact replica of the software on the primary, I'm not sure how the
Secondary would cope with this...
Thanks again guys,
Cheers,
Jason
________________________________
From: Mulnick, Al [mailto:Al.Mulnick@xxxxxxxxxx]
Sent: 02 March 2004 15:54
To: [ExchangeList]
Subject: [exchangelist] RE: Exchange Server Redundancy
http://www.MSExchange.org/
I'll offer both for what it's worth.
Clustering is not a redundancy solution. It's a high
availability solution (HA). Redundancy infers no downtime while HA
infers that you can withstand a hardware failure and can be up and
running much more quickly than you could with manual intervention.
For 30 users you want to weigh the costs. You can achive this,
but wouldn't it be cheaper and almost as fast to have the parts on hand
and just replace them if they go bad? Hardware is fairly reliable these
days and that can be more cost effective and easier to work with.
Clusters are only a little more difficult than a standalone (IMHO) but
they do have additional licensing costs for many third party
applications that you use to support your infrastructure. AV, Backup,
etc fit this category typically.
As for active/active clusters with other apps on them. You can
do this. It is possible, but again the complexity goes up with each
application as does the requirement to monitor more closely and
provision more appropriately in case of failover (think about it, if you
fail over a node due to hardware failure, you have to have the resources
to absorb the added burden. This often indicates bigger hardware
components to handle the load.) Multiple apps on an Exchange server are
not always straightforward and easy as Exchange likes to live alone as
do other apps. I'll reiterate that it can be done, but is it worth it
in your environment?
, and safeguards
check out http://www.microsoft.com/exchange/library for some
helpful docs.
Al
________________________________
From: Jason Merrique [mailto:j.merrique@xxxxxxxxxxxxxxx]
Sent: Monday, March 01, 2004 7:15 PM
To: [ExchangeList]
Subject: [exchangelist] Exchange Server Redundancy
http://www.MSExchange.org/
Hi All,
One of our exchange servers experienced a hardware failure this
morning (excellent start to the week!), and as it was the main mailbox
store, it caused a few hours of downtime for most of our users. To
prevent this from happening again, I'd like to have a certain amount of
redundancy. I understand that in a cluster of exchange servers this is
possible as they effectively act as one logical exchange server.
Is it possible to achieve the same level of redundancy without
setting up a cluster, by synchronising the mailboxes between the two
servers?
Would a cluster be overkill for our two servers and 30 odd
users?
As part of an exchange cluster - would it be possible for the
server to take on other tasks as an individual?
If you could offer personal advice, or a recommendation of
literature, that would be excellent.
Cheers,
Jason
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