Some customers ask why parallel SCSI support was removed from Windows Server 2008.
Failover Cluster in Windows Server 2008 intents to achieve the highest standard of reliability. For that, every hardware component has to be marked as “certified for Windows Server 2008”, and pass all tests in the Failover Clustering Validation tool. One of the conditions is that the SCSI device must support certain SPC-3 commands for the cluster service to work. Parallel SCSI does not support some of these commands, so it was dropped from Failover Clustering in Windows Server 2008. Furthermore virtually every major vender is deprecating production and support for parallel SCSI.
Windows Server 2008 Failover Clustering supports the following newer and more reliable shared bus types: