SDS performance

Hello everybody, Our is planning to upgrade IDS from 9.4 to 11.50 along with hardware upgrade which includes FC attached disk array that will be shared by two servers. It looks like we can try to use what is called Sared-Disk- Secondary server. I've searched this group for SDS but found nothing. Does that mean nobody is using or even interested in that feature? If anybody has experience with SDS could you please share some information on that. Particulary, would it affect primary server performance considering secondary server will not be used until we change our application to use it for read-only queries? I haven't searched for information on automating primary-secondary failover process but may be somebody could point to some good reference on that. Thank you Alexander