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Exchange 2010 single CAS and CAS Array

Posted on 2011-03-08
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Last Modified: 2012-05-11
I have 2003 and 2 owa servers right now. I'm migrating to 2010, I have 1 server already setup running the hub, Cas and Mailbox roles already. I will in the future probably want to add another exchange 2010 server so that I can have a DAG.

but from what I understand having a second CAS server will not help with load balancing since I don't have a CAS Array. So does that mean all my internal clients will connect to only 1 Cas server and ignore the other even though I have 2 Cas servers available?

Also will all incoming/outgoing email go to only 1 Cas server and not the other.

As for the San certificate, if i have 2 exchange 2010 servers would I need to have all the info for both like below:

owa1.domain.com
owa2.domain,com
autodiscover1.domain.com
autodiscover2.domain.com
CAS1 server FQDN
CAS1 server name
CAS2server FQDN
CAS2server name



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Question by:iamuser
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Akhater earned 500 total points
ID: 35072440
Oki you are mixing things up a bit so I will try to explain it my way and then pleasee feel free to ask any question you have

1. CAS array has nothing to do with load balancing they are 2 different things, you can have a CAS array without any NLB
2. It is always best to create a CAS array even if you have only one CAS specifically for the reason that when you want add a cas server all will be ready for it. I strongly advise you to create your CAS array and change the rpcclient access server on your databases BEFORE migrating the first mailbox to exchange 2010
3. Your emails go through the HUB servers and not the CAS servers
4. for the certificater you don't need the CAS1 and CAS2 names nor FQDN you only need you cas array

now hit me with the questions :)
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by:iamuser
ID: 35072600
1.) that is correct, I have 1 exchange server with no NLB. And after looking and digging around  I'm afraid of 2 things,

OWA access/mail delivery to only 1 server and failure of the CAS server internally.

basically at this point I can't break my 1 exchange server and reinstall a 2 cas/hub server and 2 mailbox servers with Dag on the mailbox and Cas array on the cas/hub server.

So what I want to do (something I found/read here). Is to have 2 full exchange server running DAG. Have CAS Array in DNS with the ip address pointed to the DAG IP. Have all the clients point to the Cas array. And configure the RpcClientAccessServer to point to the Cas Array name.

My only issue is how will incoming emails be routed? Do i point my smart host to the Cas array IP or the actual CAS iP?




 




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by:Akhater
ID: 35072626
wheen you say

>>basically at this point I can't break my 1 exchange server and reinstall a 2 cas/hub server and 2 mailbox servers with Dag on the mailbox and Cas array on the cas/hub server. <<


Why is that ? you can't have 4 servers  or what is the problem ?

do you already have mailboxes on your 2010 ?
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by:Akhater
Akhater earned 500 total points
ID: 35072682
>>Is to have 2 full exchange server running DAG. Have CAS Array in DNS with the ip address pointed to the DAG IP. Have all the clients point to the Cas array. And configure the RpcClientAccessServer to point to the Cas Array name. <<

This will give you High Availability but NOT load balancing all your clients will be connected to one of the servers




>>My only issue is how will incoming emails be routed? Do i point my smart host to the Cas array IP or the actual CAS iP?<<

CAS array ip
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Author Comment

by:iamuser
ID: 35072797
>>basically at this point I can't break my 1 exchange server and reinstall a 2 cas/hub server and 2 mailbox servers with Dag on the mailbox and Cas array on the cas/hub server. <<


Why is that ? you can't have 4 servers  or what is the problem ?

do you already have mailboxes on your 2010 ?

Mailboxes haven't been migrated yet but I don't have the extra licenses for 4 servers. Time is also another issue at this point as we have to do the migration away from 2003 as soon as possible. Unless you know of a easy way for me to remove the mailbox  role from the existing server without causing any ripples.



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by:Akhater
ID: 35072837
removing the mailbox role is very easy i wouldn't even worry about it a bit, however the 3 extra exchange licenses are another issue.

You have a decision to take 4 servers (2cas/hub and 2mbx) or 2 servers all in all so I know what to focus on in my discussion
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by:iamuser
ID: 35072849
okay, I'll have to go to management and see what they say. I'm sure they won't be happy for the 3 additional license.

I guess with high availlability I can at least fix a down CAS easily.

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by:Akhater
Akhater earned 500 total points
ID: 35072918
actually it is 2 additional licenses since you already need 2 for you dag :)

in all cases you need to

1. create a CAS array
2. change your RPC CLient access to that Cas array name

Now if you have 4 servers you will create a DAG between your 2 mailbox servers and a windows NLB betwen your 2 CAS servers, this will provide you full redundancy and load balancing for both your CAS and your mailbox servers


if you decide to go for 2 servers all in all as far as mailbox is concern nothing changed you will need to create a DAG between them. but for you CAS you can't create a windows NLB anymore since WNLB and Cluster are cannot coexist so you are left with 3 options

1. Use a hardware load balancer
2. Use the DAG IP for you cas array IP: cons is that you have no load balancing but you do have High availability
3. Use DNS round robin: cons is that if one of your cas servers fail 50% of your users will be disconnected until you change DNS entries and they refresh but you do have load balancing


so you will need to weight the between these 3 choices
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by:iamuser
ID: 35073107
Thanks I think I will go with the option number 2 as I just spoke with someone in management and the response was  " how much do you want to spill".

As for the SAN certificate name, all i need then is:


owa1.domain.com
owa2.domain,com
autodiscover1.domain.com
autodiscover2.domain.com
array.domain.com

is there any harm to include the CAS1 and CAS2 names and FQDN?
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by:Akhater
ID: 35073123
no harm to include them, the certificate will be more expensive
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Author Comment

by:iamuser
ID: 35073568
but this info should be on the SAN

owa1.domain.com
owa2.domain,com
autodiscover1.domain.com
autodiscover2.domain.com
array.domain.com

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by:Akhater
ID: 35073582
yep
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Author Comment

by:iamuser
ID: 35073707
great thanks, just 1 more thing that I just realize, for autodiscover.domain.com, having 1 will be autodiscover.doman.com but with 2 servers? Am i okay with literally naming it as autodiscover1.domain,com and autodiscover2.com?

Assuming my mail server is Mail and my domain is acme.com. Is

autodiscover.acme.com
autodiscover2.acme.com

going to work on the SAN?

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by:iamuser
ID: 35073714
I have 2 mail servers

Mail server is mail
mail server 2 is email

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by:Akhater
ID: 35073733
1 autodiscover pointed to the cas array ip no autodiscover1 and autodiscover2

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Author Comment

by:iamuser
ID: 35073752
so all I need then is just

owa1.domain.com
owa2.domain,com
autodiscover.domain.com
array.domain.com

these would be optional

CAS1 server FQDN
CAS1 server name
CAS2server FQDN
CAS2server name

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Expert Comment

by:Akhater
ID: 35073771
nop you need only owa.domain.com not owa1 and owa2
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Author Comment

by:iamuser
ID: 35073902
I assume it's only 1 autodiscover.domain.com and OWA.domain.com on the SAN because if i have 2 cas servers it would probably mean:

- I have a DAG and it would point to the DAG IP

or

- I have a Cas array and it would point to the Cas array

is this correct?



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by:Akhater
ID: 35073914
yep all you go for DNS round robin as explained before

you have 2 cas but they act as one farm
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Author Comment

by:iamuser
ID: 35073928
got you, and If i choose not to go with DNS round robin I'll have HA but no load balancing
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Expert Comment

by:Akhater
ID: 35073961
yep
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Author Comment

by:iamuser
ID: 35073982
you are the man, thanks for everything.
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Expert Comment

by:Akhater
ID: 35073990
you are welcome
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