Exchange 2010 Architecture Part – 1

Consolidation of Store Access….

In Exchange 2007 all clients would connect to CAS server except the MAPI Outlook to access their mailboxes.
In Exchange 2010 all clients will connect to CAS servers to access their mailboxes.

RPC Client Access service….

Outlook data connections go to CAS instead of connecting to directly MBX servers
Replaces the DSProxy interface by providing an address book service on CAS
Public folder connections connect directly to MBX server but again through RPC client Access.

Why was is it introduced then…?
Provides better client experience during switch over/failovers
Supports more concurrent connections/mailboxes per MBX server

How directory referral works…?
1. Outlook calls get-Address book server API
2. CAS queries AD to confirm below points:

  • Mailbox location (AD Site)
  • Mailbox version
  • RPCClientAccessServer property of mailbox database

3. CAS tells outlook which CAS server or array should be used for directory requests.
4. Outlook connects to the appropiate CAS

Note : If mailbox is still in 2003 it will again query DSProxy component of DSAccess from exchange 2003 MBX server.

Outlook anywhere clients utilize the Address book service on CAS for directory related querie.

Does this new behaviour ensure that outlook can write changes to AD for the following scenarios….?

  • Distribution group membership
  • Delegate management
  • Certificate management

Yes – when the Address Book Service detects modifications for one of the above scenarios, it will utilizes the appropiate cmdlet to commit the change to AD assuming user is scoped & authorized to make those changes.

  • Add/Remove-DistributionGroupMembers
  • Set-Mailbox-PublicDelegates
  • Set-Mailbox-UserCertificate-UserSMIMECertificate

If planning on deploying more than 8 CAS servers in a load balanced array, consider deploying hardware load balancing solution. (Although it scale 32 host having NLB Array)

Transport Roles

Shadow redundancy: Provides redundancy for new messages for the entire time they are in transit. Transport database becomes stateless. Eliminates need for RAID’s, which reduces 50% write I/O.
Dumpster changes: Database replication is now used to control which messages remain in dumpster. When message has been replicated to all database copies, message is truncated from dumpster
Dumpster size is now based on log replication latency and frequency.

To be continued….!

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