As i discussed here earlier that we are going to move in clustering environment soon. For that ,we wanted to buy SAN. But, before doing that, i have some questions, if anyone can provide some answers, that would be great. ( A ) what is the recommended I/O rate that we will need for our SQL databases? --> How to find this figure. ( B ) What is the recommended number of disk drives that we should place in our SAN to achieve this I/O rate ( For 2 Terra byte data storage) ( C ) what is the rate of the I/O that the subsystem needs to be driven at to achieve the recommended I/O rate ( How should i know this, so based on this , we can tell the vendor to provide the disk subsystem minimum of this value) I know these question are not straighforward, but if you can give any number ( not neccessarily , Exact answers) (or) any way to find this( Direct way (or) Indirect way). that will be helpful . Because i did not find these answers anywhere . Thanks again all for your help.