Business Challenges
The client provides a range of essential support cleaning services to businesses and consumers, through national networks of workplace and retail operations. Having already undertaken a strategic IT review, the client moved away from their legacy NetWare NDS environment to a Microsoft Windows 2003 Active Directory and Citrix Presentation Servers for delivery of applications to their remote offices.
Having laid the foundations with Microsoft Active Directory, the client had to decide on a future direction for email services.
Having an extensive Lotus Notes v5 infrastructure including distributed Notes clustered servers meant that the business carefully evaluated the choices; either upgrade to Lotus Domino v6 or provide an integrated email / directory services infrastructure with Exchange 2003.
Once the decision had been taken to move to Exchange 2003 the challenges were to provide an environment that was as resilient as the Lotus Notes solution.
The Solution
As the client had invested heavily in an IBM DS6800 SAN infrastructure this solution was extended to support Wintel based servers in-addition to the IBM P-series servers for the implementation of Microsoft Windows 2003 / Exchange Enterprise clustering technologies.
The replication capabilities of the DS6800 servers were reviewed and although a distributed cluster solution appeared feasible, the cost of year-on year support and the added layers of complexities eventually ruled the solution out. Our consultants were asked to investigate alternative solutions and chose one of the leading third party replication software packages with NSI Double-Take software, to replicate the Exchange 2003 data between the computer data centre and the alternative business continuity site.
Since the client's requirement was to enable mail services to be delivered from the alternative site as transparently as possible the decision was taken to evaluate the new Microsoft Exchange 2003 Standby Cluster configuration that had become available at the start of 2006.
This standby cluster configuration builds on Exchange 2003 close integration with Active Directory and enables a standby cluster to come online when the primary live cluster fails with the same virtual Exchange server name, that the Outlook clients had previously used.
This type of solution avoids complex substitution scripts that were needed to change the Exchange mailbox server attribute on Active Directory user objects and the associated MAPI re-connection delays that were originally seen when this older solution was tested.
The main computer data centre has a standard Exchange 2003 Active / Passive cluster configuration whist the disaster recovery site has a 1-node backup cluster with the virtual Exchange services offline.
Our consultants developed customised Double-Take failover/fail-back scripts to activate the backup cluster exchange services when failure of the main site was detected and the client required failover services to commence and for the recovery back to the live cluster once the site / servers had been successfully restored.
