I don’t know why it is, but SMB on OS X Server is slower and less reliable than the AFP that it replaces. Despite Apple making it the default for OS X to OS X Server file sharing connections, AFP seems to be more reliable and has less problems with permissions.

The following script may fix the inheritance of permissions being a bit wonky:

#!/bin/bash
SHAREPOINT="/Volumes/Storage/Shared Items/Share"
serveradmin settings sharing:sharePointList:_array_id:$SHAREPOINT:smbCreateMask = “0644"
serveradmin settings sharing:sharePointList:_array_id:$SHAREPOINT:smbDirectoryMask = "0755"
serveradmin settings sharing:sharePointList:_array_id:$SHAREPOINT:smbInheritPermissions = yes