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Outlook connection problems to Exchange 2010 SP1 server with rollup 2

Posted on 2011-02-24
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Last Modified: 2012-05-11
Hi,

We are migrating our users from our  Exchange 2003 servers to our new clustered Exchange 2010SP1-servers.  We have already converted 20.000 student accounts and around 2.000 staff members.  We have 2 CAS servers in a NLB-cluster and 5 Mailbox servers in a DAG-group + 2 dedicated Public Folder-servers.  Until now everything was working fine, but starting last weekend, some outlook-clients began losing their connections (or cannot even make a connection) to our Exchange servers.  95% of the clients is not affected, but the remaining 5% is a mixture of 2003, 2007 and 2010 Outlook-clients.  OWA on these workstations works fine, and we tested with or without virusscanners and local firewalls.

We looked at the workstations, but their configuration was ok: some were configured in direct mode, some using cached mailboxes.  The effect are problems starting up, or even freezes when working for a few minutes: they can open their list of mails, but when they try to open a mail, Outlook hangs.  The load on the CAS servers is between 5-15%, with peaks at 30%.  

If we switch the communication protocol on these clients to https instead of TCP/IP (Outlook Anywhere or RPCoverHTTPS), they work fine.

The only changes we made recently is install rollup 2 for 2010sp1 on both cas-servers.  Is there a known issue that this will influence the TCP/IP-communication between clients and server?  

We are also moving more and more users each night, which results in an increased usage of the databases and client communications.  I found an article about the client throttling in Exchange 2010 SP1 and found out that our RCAMaxConcurrancy was still al the RTM value of 20, but had to be changed to the default SP1 value of 214748364.  I changed it, but there seems to be no improvement.  

so, now my questions:
1) Are there known problems with rollup2 for Exchange 2010SP1?
2) Can I safely remove this from our CAS-servers to check if this is generating the problem?
3) Which settings can be/has to be changed in the Client Throttling to improve Outlook TCP/IP communication?
4) Can those throtlling-parameters be changed on the fly, without a service- or server-restart, and are they changed instanteaneously?
5) Is there something else that can cause this strange behaviour on -some- Outlook clients?

Kind regards,
Bertin
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Question by:sysUA
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by:
Raghuv earned 500 total points
ID: 34977409
Here you go,

1) Are there known problems with rollup2 for Exchange 2010SP1?
- There are no known issues with RU 2 as such, however I have seen many customers complaining about similar issue and I guess MS is still working on it and possibly there would be fix in the upcoming Roll up.
- I have also seen this issue occuring if you have Blackberry in the environment, ensure the BESAdmin account has a different Throttling policy applied with RCAMaxconcurrecy set to $null.
- Run Perfmon/Perwiz and analyze the logs to see if you anything abnormal with your disk's.
- Run ExBPA report (health check) and ensure you do not have any errors listed (Exchange Management Console -> Toolbox).

2) Can I safely remove this from our CAS-servers to check if this is generating the problem?
- You can safely remove the RU2, but you need to ensure that all Exchange 2010 servers are on the same Service pack as well as Roll up level. So if you remove RU2 from problemtic Server, you need to remove it from all the servers as well.

3) Which settings can be/has to be changed in the Client Throttling to improve Outlook TCP/IP communication?
- There are few parameter's starting with RCA and you can see the list by doing a Get-ThrottlingPolicy | fl.
- This settings needs to be modified only if you see lot of 2915 for users complaining about RPC.
- Please do not set this value to $null. You need to monitor the situation and keep increasing. You can start with say 100.

4) Can those throtlling-parameters be changed on the fly, without a service- or server-restart, and are they changed instanteaneously?
- Once a Throttlling policy has been applied you need to wait for 15 minutes to affect in case you do not want to restart any exchange services.

5) Is there something else that can cause this strange behaviour on -some- Outlook clients?
- You need to ensure every client has the latest updates/patch installed (Office as well as Windows updates)
- If possible upgrade all Outlook 2003 clients to Outlook 2007 or 2010, as Outlook 2003 makes multiple connections to the Exchange Server especially if Outlook 2003 users are trying to open shared calenders.


I hope it helps.
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Author Comment

by:sysUA
ID: 34980194
Hi,

Thanks for your answers.  I removed RU2 from the 2 cas-servers last night (it was already removed from the Public Folder servers the night before), and rebooted them.  All problems disappeared at once: all Outlook clients are back online with a stable connection (https or TCP/IP)...

I hope RU3 will fix this issue, because it can cripple an entire organization and I did not find many comments on this issue.

Kind regards,
Bertin
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