Exchange redundancy

Posted on 2001-08-29
Medium Priority
Last Modified: 2012-08-14
I have exchange 5.5 running, and I want to create redundancy incase the server crashes.   What is the recommended way to create redundancy for Exchange 5.5.  I heard from someone that I should put exchange 5.5 on 2 servers and then balance mailboxes between the two and move mailboxes when one crashes.  Is this the best way for someone one Exchange 5.5 and NT 4.0?

Question by:ptran2000

Expert Comment

ID: 6436982
It depends on your budget and whether you are looking for uptime, data backup or a combination.  The overall idea would be to eliminate any Single Point Of Failure (SPOF's).  The best way but probably the most expensive is to cluster your server.  If you split mailboxes between 2 servers then you really don't have redundancy what you have is reduced the number of users affected when a server crashes.  But when that server crashes you still have to recover data from it and restore user mailboxes.

Expert Comment

ID: 6438177
Exchange 5.5 clustering is not great.  It works in an Active/Passive mode which means that the second server in only used when the first crashes.  You should maybe consider moving to Exchange 2000 as this support Active/Active clustering.  This means that all you hardware and investments are always utilized.  Connections are split between the two but with automatic failover if one fails.


Author Comment

ID: 6438339
robinsonbpc, the redundancy is mainly for uptime,  if for some reason the primary Exchange server crashes, then I want the other server to kick in (failover support).  My company is very dependent on email, so I want to have something up in about 1-2 hours if the primary Exchange server crashes.

Darren,  Active/Passive is fine with me as long as the Passive Exchange server can kick in within an hour or so.  I have no experience with clustering servers, do you need enterprise version of NT for this or just the standard version on NT server?  

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Expert Comment

ID: 6439876
Exchange 5.5 on NT clusters can be a pain. Plus, there seem to be precious few consultants and support people who know NT clustering. When you have cluster questions, you can't always get answers.

If you need high-availability (ie. "always-on"), I would suggest looking at Exchange 2000 and Windows 2000. Alternatively (particularly if you don't want to upgrade) you could look at standby servers and 3rd party clustering options. Here are two examples - I can't vouch for their compatibility with Exchange, but they're worth a look:

Legato Co-Standby Server:

NSI DoubleTake:


Accepted Solution

robinsonbpc earned 200 total points
ID: 6440157
To answer your question about 5.5 and clustering: Exchange 5.5 and NT 4 in a clustered environment requires the Enterprise edition of NT.  In this configuration the passive node can take over operation within minutes if not quicker depending on how you set it up.

Again as I mentioned originally you will have to weigh your needs against your budget.  Typically it is better to have the latest software out (Exch 2k, Win 2k) as mentioned above however this is another cost you incur.  Exch 2k on Win 2k does handle clustering better than Exch 5.5 on NT 4.

Another idea that gives a good trade off between cost & redundancy is to invest in a good server and ensure you have a proven backup/restore plan.  In this method you would put your redundancy in your server.  Ensure it has multiple power supplies, a hardware RAID controller, a RAID array on quality high speed disks, etc.  With as much of this as possible being hot swappable.
LVL 44

Expert Comment

ID: 7270516
Hello ptran2000

this question is open for more then 2 months
time to clean up
if not stated otherwise

my recom will be
-points to robinsonbpc
-this will be finalized by an EE Moderator
-with no further update (15.09.2002)


posted by ToolzEE v1.0

Expert Comment

ID: 7297244
Question has been closed as per recommendation

JGould-EE Moderator

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