MSExchange.org Monthly Newsletter of April 2008 Sponsored by: InterMedia

Welcome to the MSExchange.org newsletter by Henrik Walther, Exchange MVP, MCA: Messaging (Exchange Ranger) Apprentice, MCTS Windows Server 2008, MCITP Exchange 2007, MCSE 2003 Messaging/Security. Each month we will bring you interesting and helpful information on Exchange Server. We want to know what all *you* are interested in hearing about. Please send your suggestions for future newsletter content to: henrik@msexchange.org

1. Exchange Server 2007 Mailbox Store & TCP/IP Connection Limits

Welcome to the April 2008 edition of the MSExchange.org newsletter!

This month I wanted to talk about the TCP/IP as well as store connection limits that exist in Exchange Server 2007. Although Exchange 2007 is based on 64-bit architecture meaning this version, among other things, is capable of using much more memory than Exchange 2003, which could not use more than 3GB of memory. This also means that you, for instance, can store a lot more mailboxes on an Exchange 2007 Mailbox server than was the case previously. In addition, a Client Access server can handle a lot more client connections than a legacy front-end server could.

With Exchange 2003 it was not recommended to store more than approximately 4000 mailboxes on a dedicated Exchange 2003 Mailbox server and this was when the /3GB startup parameter was added to the Boot.ini file. Of course this depended on the user mailbox profiles, concurrent connections as well as what clients were used within the organization. But if you did add more than 4000 mailboxes, you would often experience issues with virtual memory fragmentation, kernel memory, non-paged as well as paged pools exhaustion, etc. Exchange 2007 fixed all that and more, as you can add up to 16TB of memory to an Exchange 2007 server. Bear in mind that it is not recommended adding more than 32GB, since more memory does not make sense. This is because 32GB is the most cost-efficient maximum memory configuration.

So everything is perfect then, I can just store as many mailboxes on a Mailboxes server as I want to right? Nope unfortunately this is not so. You see fixing the memory limit in Exchange Server 2007 just meant that we reached another bottleneck in the product. The Exchange Information Store has a maximum limit of 60,000 connections. After that limit is reached, you will experience serious performance issues. Ok, but 60,000 connections is 60,000 Outlook users connecting to the Mailbox Server, isn't it? No, as most of you guys know, Outlook uses MAPI over RPC (yes correct, Outlook 2007 also uses Exchange web services) to communicate with Exchange, and depending on the type of mode the Outlook client is running in (online mode, cached mode, Outlook Anywhere) as well as other factors, different numbers of TCP/IP as well as RPC connections will be established between the clients and an Exchange 2007 Mailbox server. Especially Outlook Anywhere clients establish a lot of RPC connections to a Mailbox server. A general best practice is to have no more than 60,000 concurrent Outlook connections to a Mailbox server if you are strictly using Outlook clients in online mode. 30,000 mailboxes if you are using clients running in cached mode and 10,000 mailboxes if only Outlook Anywhere clients connect to the mailbox server.

The above numbers is strictly with the Exchange 2007 Mailbox server in mind. There are other potential bottlenecks in ISA Server and/or on the Client Access Servers in the organization. The bottleneck on a Client Access server is the number of TCP/IP connections that can be established.

So will installing Exchange 2007 on Windows Server 2008 ease these bottlenecks? Well, Windows Server 2008 would not be able to fix the store connection limit, as this limitation lies within the Exchange product. But what about the TCP/IP limitation then? Good question! Windows Server 2008 will, like Windows Server 2003, still have a limitation of 65,535 outbound connections but per IP address not per server. This means that configuring multiple IP address on the Exchange 2007 server would allow more outbound connections, which would be very useful for Client Access servers in large organizations.

If you want to read more about the above scalability limitations for an Exchange 2007 Mailbox server, be sure to check out the new Storage Design for Exchange Server 2007 technical white paper released by Microsoft IT Showcase recently. It is a must read!

Cheers,
Henrik Walther

Note:
Should you have any ideas for content in future editions of the MSExchange.org newsletter, you are more than welcome to shoot me an e-mail at Henrik@msexchange.org

2. Order Henrik Walther's Exchange Server 2007 book

3. MSExchange.org Learning Zone Articles and Videos of Interest

We have a great group of articles in the Learning Zone that will help you get a handle on your most difficult configuration issues. Here are just a few of the newer and more interesting articles:

• Deploying an Exchange 2007 SP1 CCR Cluster on a Windows Server 2008 Failover Cluster - Part 2: Forming and Validating the Failover Cluster
• Designing a Multi-Server Environment based on High Availability and Role Based Setup
• Managing Standby Continuous Replication (Part 1):
• GroupWise to Exchange 2007 - Interoperability and Migration (Part 4)
• The Exchange Pickup Folder
• Load Balancing Exchange 2007 SP1 Hub Transport Servers using Windows Network Load Balancing Technology (Part 2)
• Continuous Backup for Exchange Server with DPM 2007 (Part 3)
• Managing Resource Mailboxes in Exchange Server 2007 (Part 3)
• Troubleshooting Out of Office
• Load Balancing Exchange 2007 SP1 Hub Transport Servers using Windows Network Load Balancing Technology (Part 1)
• GroupWise to Exchange 2007 - Interoperability and Migration (Part 3)

4. KB Articles of the Month

Here are some interesting and useful MSExchange related articles posted by Microsoft in the last month:

Exchange 2007

• Multiple Exchange Server 2007 services do not start when you upgrade a computer that is also running Windows Server 2003 to Windows Server 2008
• Error message when you try to uninstall Exchange Server 2007: "Process execution failed with exit code 5"
• Event ID 4000 is logged when an SMTP server that is configured to use the Integrated authentication method negotiates GSSAPI authentication with an Exchange 2007 receive connector that is also configured to use the Integrated Authentication method
• Some users cannot access Exchange Server 2007 Outlook Web Access after you create new mailboxes or migrate existing mailboxes
• The Exchange Server 2007 installation fails during the PrepareSchema step, and you receive an error message in the Setup log
• Error message when you check the properties of a contact in Outlook: "The name cannot be resolved. The bookmark is not valid"
• The account test process is failed when you try to configure an Outlook 2007 client to connect to an Exchange Server 2007 mailbox by using a POP3 connection or an IMAP4 connection
• The Autodiscover service fails for some Outlook 2007 users after you install Exchange Server 2007 Service Pack 1
• An e-mail message is in disorder and is unreadable in an Exchange Server 2007 environment
• An Exchange 2007 edge server does not rewrite the sender address for externally bound messages in an Exchange Server 2007 Service Pack 1 environment
• The Edgetransport.exe process may stop unexpectedly on a Exchange Server 2007-based edge server

Exchange 2003

• An update to a recurring meeting request that is sent from Exchange Server 2003 does not occur on the receiver side
• Event IDs 9582, 9665, and 9175 may occur on a server that is running Exchange Server 2003
• The Exchange ActiveSync process is unsuccessful, and an error code is returned to the mobile device in Exchange Server 2003
• ActiveSync cannot synchronize a mailbox if the Exchange Server 2003 store contains a corrupted e-mail item
• Exchange Server 2003 users cannot use the Exchange Server 2003 Connector for Lotus Notes to send e-mail messages to Domino recipients who have ANSI 1252 8-bit characters in their names
• The Inetinfo.exe process may crash frequently after you enable regtrace on an Exchange Server 2003 server
• The contents of attachments are changed to match the contents of the first attachment in Exchange Server 2003 when an e-mail message contains multiple attachments that have DBCS characters in their file names
• Description of the March 2008 special daylight saving time (DST) update release of Exchange Server 2003 Service Pack 2
• Tasks are unexpectedly deleted even though they are not past their age limit in an Exchange Server 2003 environment
• The W3wp.exe process may crash frequently on Exchange Server 2003 servers in an organization that has many Outlook Web Access users
• Outlook Web Access users are unable to save appointments or respond to meeting requests
• Error message when you check the properties of a contact in Outlook: "The name cannot be resolved. The bookmark is not valid
• If an SMTP connector set the Outbound Security option to "Integrated Windows Authentication," the SMTP connector does not work in the IIS Metabase when you restore an Exchange Server 2003 server by using a Disaster Recovery mode

5. MSExchange News of the Month

• New Storage Design for Exchange Server 2007 TWP Published
• Seeking Beta testers: AbsoluteProof for Microsoft Exchange
• Windows Mobile 6.1 Emulator Images Released
• TechNet Virtual Lab: Exchange Server 2007 Standby Continuous Replication
• Novell's lagging position in the messaging and collaboration market
• Lotus Notes Transition White Paper released
• Vendor Marries Google-Microsoft E-Mail in the Cloud
• TechNet Virtual Lab: Installing Exchange Server 2007 SP1 on Window Server 2008

6. Ask Henrik Walther a question

QUESTION: Hi Henrik,

Great article on CCR clustering. I have a quick question for you.

I am in the process of setting up and configuring CCR in my environment. Both nodes will be in the same data center.

Can I just use a cross-over cable for the private nics?

ANSWER: Yes, using a cross-over cable for the private (heartbeat) network between two fail-over cluster nodes on a CCR-based clustered mailbox server works just fine.