In his recent blog, Hitachi Data Systems’ CTO, Hu Yoshida, discusses the top 10 business trends that will impact IT in 2015. Number four on his list is “Software Defined Everything”. One of the theoretical selling points of software defined initiatives is that they allow IT planners to build infrastructures out of commodity hardware, which should save the data center a significant sum of money versus custom built hardware. Don’t believe it, there is a cost associated with making commodity hardware reliable that must be taken into account before IT planners decide that a software defined solution leveraging commodity hardware is actually worth the savings.
What is the Real Cost of Commodity Hardware?
The key to the software defined crowd’s claim is that it’s ok to use less reliable hardware (a.k.a commodity) because software defined solutions can build in multiple points of redundancy. And for the most part this is accurate. But that redundancy costs money.
For example many software defined storage solutions leverage a replication data protection strategy to provide data redundancy and compute redundancy. In a three-node starter system, a virtual machine’s data on one node is replicated to the two other nodes. If the server or storage in the server on node one fails, the VM can be restarted on another node.
This sounds great, but take this to scale and it gets expensive. If you stay with the above replication model the commodity infrastructure will require 3X the storage capacity. That means 3X the network activity and potentially 2X the compute capacity, all for the privilege of using commodity hardware.
Compare this software defined enablement of commodity hardware to a more traditional, less headline grabbing SAN architecture backed by a quality SAN array. Data is protected on the device and consumes no additional server CPU or storage network bandwidth. Using RAID 5, RAID 6 or some form of erasure coding, the storage system can provide redundancy for an extra 20% to 30% of actual data, not 300% (3X).
Also keep in mind that this environment delivers the most important attribute to IT, predictability. The storage network and storage CPUs are dedicated to the task at hand.
For more on the top business trends impacting IT join Hu and myself for our webinar on December 10th at 12pm ET, 11am CT, 9am PT.