Pop QuizQ: What's the maximum number of disks per SCSI Controller?
A: It depends.. On your VCP exam, you would have said 15. Correct.
Although if you want to clone or snapshot and quiesce a VM, the maximum is 7 disks per SCSI controller.
Each SCSI Controller can control 15 disks and the quiesced snapshots in Windows 2008 require one available slot per existing disk.
If you have more than 7 disks, the clone / quiesce part will fail, and you'll have the following errors in vCenter and the VM's vmware.log:
An error occurred while quiescing the virtual machine. See the virtual machine's event log for details.
2014-12-22T00:19:16.188Z| vmx| ToolsBackup: not enough empty nodes (needed 8, found 7)
2014-12-22T00:19:16.188Z| vmx| ToolsBackup: changing quiesce state: IDLE -> DONE
2014-12-22T00:19:16.188Z| vmx| SnapshotVMXTakeSnapshotComplete done with snapshot 'clone-temp-1419207556192169': 0
2014-12-22T00:19:16.188Z| vmx| SnapshotVMXTakeSnapshotComplete: Snapshot 0 failed: Failed to quiesce the virtual machine. (40)
It's explained in http://kb.vmware.com/kb/2015181.
Just one more way snapshots can bring you pain.
Updated 23/12/2014: This affects Windows 2008 and above (ie: Win 2012), and is still an issue in vSphere 5.5. KB article will be updated.
For the lazy, see here:
Creating a quiesced snapshot of a Windows 2008 virtual machine fails with the error: Snapshot 0 failed: Failed to quiesce the virtual machine.