Better late than never, here is a partial list of the cool new things in Windows 2003 SP1 clustering (yeah yeah, I know Windows 2003 SP1 has been out for quite a while now… just shows you how far behind I am in my blog posting )

• Quorum replication algorithm redone so it’s more robust.
• Cluster administrator is now multi-threaded. Very responsive for large clusters with lots of resources.
• “/registerdns” switch added to cluster.exe to allow network names to reregister without taking an outage (ie – cluster res “cluster IP address” /registerdns)
• DisableClussvcMediaSense cluster private property added to allow win2k functionality for media sense
• New registry path to override setup fior unique buses to boot from SAN (see KB.886569 for more info).
• Setup wizard is smarter about identical storage device added on two different buses.
• Additional disk health monitoring (in addition to SCSI reserve, now checks physical disk availability every 3 seconds by writing to sector 12).
• Readonly CHKDSK replaced with Vrfydsk
• More SAN friendly using Unique IDs – no bus reset floods, fewer event ID 1209, improved disk arbitration times
• New “Maintenance Mode” for physical disk resource. Supresses all volume health checks to allow maintenance to be run: chkdsk, format, VSS volume level restores, etc.
• Full support for iSCSI clusters (policy)

So, there’s a lot of good reasons to update your Exchange 2003 clusters to Windows 2003 SP1. Double-check with your storage vendor to make sure W2k3 SP1 is in their support matrix. Make sure you also apply the KB.841561 hotfix for Exchange!