Hi All,I'm Jay and I'm the main Sys Admin for the Exchange mail server at a reasonably large company in the UK.I was hoping for other peoples opinions on where I go with the Exchange upgrade I've been tasked with. I'll give you a quick run down of what we currently have...Currently we have a Marathon everRun FT cluster (http://www.marathontechnologies.com/) although this has not proved to be the best solution for us since we have expanded quite rapidly and the version we have only allows 1 cpu on the virtual server. We've had several performance issues with the current setup and I have recently installed a 2nd server (as a short term fix) to ease the load on the FT cluster.We have roughly 1000 mail users and are currently at around 600gb of mail with all the mail stores combined.We have a lot of IMAP users (Mac, Unix etc, probably 30-50% of mail usage is IMAP)Before anyone suggests it, I cannot implement limits for mailboxes. This is probably the cause of a lot of our problems to be honest, some of the mailboxes here are in excess of 10gb!I was planning on migrating to Exchange 2007 but I have read about quite a few issues with IMAP and Exchange 2007 with no resolution coming until the next release of Exchange. Because of this I'm currently thinking about sticking with Exchange 2003.Do I go for something like a 4 node Active/Passive Exchange 2003 cluster? These servers would be in different machine rooms with storage provided by SAN.I could go with the Marathon cluster setup again as the newer version allows for more CPU's, probably 2 virtual servers (so 4 machines total) I think we will still be limited to 2 CPU's per server though.Or I could go with Exchange 2007 clustering.What are other peoples opinions? Reliability and performance are the main issues for us.All opinions appreciated!Cheers,Jay

Hello Jay, I haven't personally seen to many issues with Exchange 2007 IMAP. The biggest issue I've run into with IMAP is migrating from a non-exchange IMAP systems to Exchange 2007. If you are currently running 2003 and really don't want to go to 2007, I'd focus on extending the life of the current system instead of implementing a new system. If your current system can last until the next version of Exchange, you'll be in the best position, but there is no guarantee when that will be available. You have some large mailboxes, and since you are considering clustering, I'm assuming that it is a critical system. 2007 does give you CCR to protect all of that e-mail from storage failure. Exchange 2007 can use less expensive storage, but with CCR cluster you need twice as much. Exchange 2007 is a 64 bit platform that can take advantage of a lot of memory, which is likely to maintain or improve performance. Joseph M. Durnal

Hi Joseph and thanks for the reply,I was hoping to move to Exchange 2007, I was just put off by of the IMAP issues I have read about. I wonder if Exchange 2003 has the same issues as we have had our share of issues with people trying to use IMAP from Exchange. It seems mainly to be from Mac clients with us. The current Marathon Cluster really needs replacing, it's just not up to the job anymore. Having split the load onto multiple servers, it's performing much better but I really need to have a more permanent solution. I'm guessing I can install 2007 alongside our current Exchange Server? What issues should I expect with this? I've heard of routing issues between 2003 and 2007 - are you aware of this?I've read about CCR, looks interesting. I guess I need to have a play with it and see what I think - I was just a little worried about setting it up alongside 2003.Many thanks again for the reply,Jay

CCR is easy to play with in virtual PC or VMware. Routing between 2003 & 2007 works fine. Of course, different configurations could lead to different types if routing issues with any version. One of my customers is doing a migration from a unix based imap system to Exchange, but they aren't replacing all of their clients right away, so there will be many windows thunderbird clients in the mix. We haven't really run into any specific imap problems during testing. Joseph Durnal