Transition to Exchange 2010 and add additional sites

[loyalist]

Currently have Exchange 2003 in FE/BE configuration in single site, want to transition to Exchange 2010 and add 2 additional sites. Sites are in US, UK, & CA so ideally looking for better performance with multi-site deployment, allow users in each site to have local access to mailboxes. Have purchased 3 Dell R510 to use as CAS/HUB/Mailbox in each site and 3 Dell R410 to use as Edge Transport in each site. Initially thought I could do this by implementing DAG across databases in all 3 sites (have Windows 2008 Enterprise licenses), but now not quite so sure. Concerned about access through edge servers at each site, shouild I use Round Robin DNS, with MX records? Also not sure about WNLB for CAS versus using DAG. Performance for each site was main concern but would like to have some level of redundancy, as I understand you cannot use both WNLB and DAG unless you have purchased seperate load balancing hardware. Really just looking for some solid advice and reliable documentation as to best way to proceed, budget is gone so no additional hardware purchases are possible. Have been doing alot of research, just not finding exactly what i need.

Thanks in advance

 

[58sniper]

WNLB can't be used if you're going to do DAG. Period.

Not sure I would have done 3 Edge transport boxes, as the likelihood of efficient message routing is diminished unless you have different SMTP domains for the different sites.

Doing a DAG across all three sites is trickier than you might want. Where is the quorum going to be?

You don't mention the size of the org or how many users are in each location. But in many orgs, you don't *need* local Exchange servers. Split the DAG between two sites with the usual failover planning, and have all users connect to the mailboxes.

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/

 

[loyalist]

WNLB can't be used if you're going to do DAG-Agreed, one or the other, but you can purchase a 3rd party load balancer to use with the CAS instead of using WNLB, which of course I can't do because of budget so I am considering that I might be better off using WNLB for the CAS and forget about DAG altoghter.

3 edges were so that if one site went down inbound mail would continue to flow through an edge at antother site-heard about using round robin mx records for this.

Quorum would be in primary site, this does sound bad, so 2 votes in 1 site, and 1 vote in each of the other site, if primary goes down then so does DAG.

200 users in site A, 100 in B, 100 in C.

This is why I am posting, appreciate any and all advice.

Thanks

 

[58sniper]

From an HA perspective, I'd take DAG over a CAS array any day.

As for Edge, think about optimal message routing. If you do round robin, 1/3 of all inbound email would come in to site A, and 1/3 to site B, and 1/3 to site C. Is that really what you want? Generally, in enterprise designs that I do, I have all mail come in to site A via MX record with lowest cost. Then, 2nd site via MX with a higher cost. So, under normal circumstances, 100% of all mail comes into one location. Remember that you must have the same level of protection at every ingress and egress point to avoid problems.

Think of the probability of a dual site failure, and your ability to maintain business. For a business your size, it's HIGHLY unlikely you'd ever have a dual site failure.

With Outlook Anywhere, Exchange Active Sync, and Outlook Web App, having the servers in just two locations would make sense. Other than initial caching of mailbox content, most access is to local cache, and not the server.

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/

 

[loyalist]

Sorry for the delayed response, yesterday was a bit crazy.

So following your recommendations I could do something like this:

Site A: Load balance 2 Edge servers using WNLB, install 2 CAS/HUB/Mailbox servers implement DAG.

Site B: 1 Edge server with MX record higher than Site A, install 1 CAS/HUB/Mailbox

Would the DAG in site A include Site B, I would assume so, then I would have DAG over the WAN between sites, so need a good link.

Considering this project will begin as a transition from a single 2003 FE/BE, the existing BE has 4 databases, when I install the 2nd & 3rd C/H/M will these databases be automatically populated in the new servers via the exchange organization? I would like to have active users in Site A & B.

If I am putting a DAG in Site A and I can't load balance CAS, then should the second server only be setup as a mailbox server or can it have all roles? Can I have C/H/M roles on the server at Site B?

Assume I would use the same SAN certificate on all 3 servers, but should I add additional name for Site B server or keep same certificate names for all 3?

Thanks again for your advice.

 

[58sniper]

You'd still need a hardware load balancer if the DAG members are also holding the CAS and HT roles.

Don't NLB the Edge boxes.

No - databases don't do anything when you add servers. Everything is a manual process, and there are MANY in a migration.

Based on your questions I would emphatically recommend bringing in a consultant. There is still much planning to be done. Planning that should have been done long before hardware was ordered.

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/