The Real Price of Enterprise Storage
One of the pet peeves that come with the territory when deploying SSD systems is being compared to the price of consumer disks. I might be bothered in particular because I have seen how rapidly the price has declined since Flash entered the field. I remember that it was not very long ago (2004) that SSDs were thousands of dollars per GB! Now, as the price of SSDs comes much closer to what high performance enterprise disk systems cost, the difference does not seem that bad to SSD veterans.
There is a general disconnect between what hard drives cost in the consumer market and what the disk based enterprise storage systems cost per GB. I am sure that IT administrators get offers from end users all the time to personally buy a 1 TB drive for $80 to increase the size of their exchange mailbox.
So where can you find what enterprise storage systems cost?
The best source available is the Storage Performance Council’s (www.storageperformance.org) published data on the benchmark results of various enterprise storage systems, and one of the requirements is that the full costs must be disclosed. When you look at this data in a few different ways you can draw some general conclusions. First, the obvious one, disks are rapidly getting cheaper per GB (below is some historical $/GB data on test results from systems with more than 100 disks):
However disks are not getting cheaper – they are just getting bigger. Enterprise disks are very expensive once you include the costs of the storage controller, switching, and maintenance. Below is the cost of a solution divided by the number of disks:
From these costs it is easy to see how there is a business case for deploying a solid state solution to eliminate 20 disk drives (or more). You can always get more capacity with disks at a lower price point than SSDs and that will continue for a long time. However, since the price per disk is so high, for smaller capacity, high performance workloads, SSDs are just cheaper. The price point of a 15K RPM drive behind a storage controller is so high that you don’t have to be at the extreme end of the performance curve anymore to justify SSDs.
Realistically, once you are putting in 2-3 times as many drives for performance as you need for capacity, a serious investigation of SSDs should follow.