Exchange 2000 Migration

Migration Planning

• Two Exchange migration paths

• Two Phase of the upgrade

• Co-existence

• Move Mailbox Wizard

• Checklists

• Resources

• Download my Exchange Migration eBook $4.95

Guy's degree of difficulty

Hardest Install= 10

  9 Exchange 2000

  7 SQL 2000

  6 NT 4.0

  4 Exchange 5.5

  3 Windows 2003 Server

  2 XP

Easiest Install = 0

Two Exchange 2000 migration paths

Following my military campaign analogy, take a minute or two to decide your overall strategy.  There are two paths for migrating from Exchange 5.5 to Exchange 2000 and a wrong decision here could cost you dearly.

1. 'In Place' Upgrade.  Just upgrade Exchange 5.5 where it stands. Convert the Exchange 5.5 server quickly to Exchange 2000 with no co-existence.  Just remember that before you do this you must upgrade NT 4.0 to Windows 2000 Active Directory.
2. Incremental migration.  A period on co-existence.  Install Exchange 2000 in an existing Exchange 5.5 site; gradually move mailboxes to Exchange 2000.  Eventually, decommissioning the Exchange 5.5 servers.

Normally I recommend strategy 2. = Incremental migration.  This is the better path because it gives more flexibility and better rollback.  With care, an incremental migration will avoid downtime, whereas an 'In Place' upgrade will need several hours to convert the store database (Priv.edb).  'In Place' upgrades are often impracticable because the old hardware is unable to run Exchange 2000.

Two Phases for your upgrade

Which ever of the above strategies you choose, there will always be two distinct phases for the Exchange 2000 upgrade.

1. To transfer Exchange 5.5 Directory Services into Windows 2000 Active Directory.
2. To move the users' actual Mailboxes from Exchange 5.5 to Exchange 2000.

Phase One

Your tactic in phase one will be to transfer the Exchange 5.5 directory database into Windows 2000's Active Directory. This database which is stored in DIR.edb contains all the naming information, for example, email addresses and distribution lists.  Microsoft provide a special tool called the Active Directory Connector (ADC) for this phase, take the time to install the ADC and test 'Agreements' before you transfer the real user data into Active Directory.

Phase Two

Phase two involves transferring the mailbox store Priv.edb, from Exchange 5.5 to Exchange 2000.  If you used Public folders in Exchange 5.5,then Pub.edb will be migrated at the same time.  The tactic is to install a new Exchange 2000 in the existing Exchange 5.5 site.  Once you remember that the mailbox is a property of the user then it is logical to go to Active Directory Users and Computers, Right click the user, Exchange Tasks, 'Move Mailbox'.

With any migration, there are always extra bits and pieces to sort out, for example, upgrading the Site Connectors to Routing Group Connectors, and configuring the new SMTP connector.  In addition, I would use the migration as a chance to appraise the new features of Exchange 2000, for example, creating multiple stores will reduce backup and restore times.  If you have not used Outlook Web Access (OWA) before, take the time to check out its new and improved features.

Co-existence - Make a plan for each Exchange component

To analyse what information passes between Exchange 2000 and Exchange 5.5, it is useful to break down their communication into the following components:

User account co-existence

Both versions of Exchange need to know about a user's directory listing.  Eventually all this information will be stored in Active Directory, but in the meantime the two systems need to synchronise databases.

I think of the SRS (Site Replication Service) as Exchange 2000's emulator for Exchange 5.5's directory services.  Microsoft have always been good at backwards compatibility, and SRS enables both versions of exchange to speak the same language.  SRS consists of a database, transaction logs and Site Consistency Checker, the later prevents duplication in multi site configurations.

ADC agreements  not only populate Active Directory with user mailbox information, but are useful in synchronising with Exchange 5.5 once co-existence has been established.

Messaging Co-existence

Once again, Exchange 2000 needs an emulator to communicate with Exchange 5.5.  While Exchange 2000 prefers to use SMTP to send messages, it will use an MTA (Message Transfer Agent) to send and receive mail from Exchange 5.5.   When examining message flow, think of the email as having two parts, a header, and a separate body containing the email text and attachments.  I think of the header or mailmsg as listing addressing and routing information; whereas the body of the message is just a block of text which is kept separately in the store database.

It is worth sketching out a diagram of the flow of messages through your organization; this will aid installation and help troubleshooting delivery problems.

Public Folder Co-existence

Public folders have have their own personality.  Their permissions are different, Author, Editor, rather than Read, Write, Change.  They have a separate replication topology and it is no surprise that public folders have their own database pub.edb, separate from the mail's priv.edb database.

Public folders have multiple components:

1. The names of the the folder, its directory entry and email address.  The new folder naming information will be stored in Active Directory, while the old Exchange 5.5 information is kept in dir.edb.
2. The folder contents, messages, notes and forms which are stored in the pub.edb.
3. Public folder structure, the hierarchy of directories.

An unwelcome by-product of all these public folder parts is, that the may replicate at different speeds and so confuse users who see the hierarchy but no underlying messages.  Fortunately, this is a temporary situation which Exchange will resolve automatically given time.

Routing Co-existence

Exchange 5.5 sites were bolted together with site connectors; these connectors route the mail to addresses within your Exchange organization.  In Exchange 2000 site connectors have been superseded by routing group connectors.   Exchange 5.5 servers communicate using RPC, so Exchange 2000 has to downgrade from SMTP to RPC when connecting to Exchange 5.5.

Another possibility for exchanging mail would be Exchange 5.5's IMS (Internet Mail Service) communicating with Exchange 2000's SMTP connector.

Move Mailbox Wizard

Firstly, let us recap on the situation.  At this stage you have installed Exchange 2000 and verified that it running properly.  Next you created a test account and successfully send and received mail.  You are now ready to move the user's mailbox from the Exchange 5.5 server on to the new Exchange 2000 server.

You are now ready to bring the Exchange 2000 member servers into production.  Once you realize that the mailbox is really an attribute of the user, the migration method become obvious.  The technique is to open Active Directory Users and Computers, and right click the user and select Exchange Tasks.  Now the Wizard takes over and shows you to move the mailbox onto the new server.

Checklist

• Active Directory is installed and integrated with DNS.
• Double check your Exchange Organisation name and email addresses. Any planned changes?
• Master the Active Directory Connection (ADC) agreements. N.B. use Exchange version of ADC
• Key question: 'How long will Exchange 5.5 and Exchange 2000 coexist?'
• Check your hardware - is fit to run Exchange 2000? For example, do you have the disk space and lots of RAM.
• What part with Public Folders play in Exchange 2000?

Traps

• The person installing is not members of the Schema Admins and Enterprise Admins
• (Plain) Exchange 2000 has a 16GB limit on the Public and Private message store.  Use Enterprise Exchange 2000 which has no limit.

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