Virtual Disk Storage
History truly does repeat itself. We are talking about the history of data storage. Every once and a while a new technology comes along that requires a new way to think about infrastructure. Notice I said “infrastructure”. I’d like to paint two analogies:
Analogy 1: RAID – Prior to RAID users stored their data on disk and if they could afford it, they backed that data up to have a protected copy of their data. When RAID came out, users were able to store their data on multiple disks appearing as one device. The benefits to this were, increased data reliability, better performance. This new technology however, fundamentally changed how disk was sold, but the questions were the same:
- How much capacity do you need?
- What type of performance does your application require?
The sales reps point of view changed. There were a number of new considerations that needed to be taken into account. First, the age old question, “Will I sell less storage “stuff?” Remember the person, at the time, selling the disk was probably also selling the backup tape and software to protect that information. If the disks are more reliable, maybe the customer won’t need as much tape? Second, when the capacity question came up, the seller also needed to know what type of RAID the customer wanted to ensure they sold them enough drives. It was no longer as simple as asking the capacity requirements and dividing it by the drive capacity at the time. Now depending upon RAID levels there was a new set of math that needed to be done. Third was the notion of performance and more spindles meant more performance so now that the capacity equation was solved for, you also needed to know the I/O requirements in order to make sure the right number of drives were sold to solve for the capacity as well as the performance.
