I have been watching the metrics on solid-state storage. There is a price-per-gigabyte metric; there is also a price per IOPS and other kinds of metrics. As price per gigabyte continues to drop, it may never catch all hard drives and it may never be on parity with, certainly, bulk-capacity hard drives, but that gap is getting narrower.
At some point, especially when you look at enterprise hard drives like the 10K and the 15K hard drives, the price gap between the cost of SSD and the cost of those drives is getting less and less. At some point it makes sense to say, "At three-to-one, maybe it makes sense; maybe at two-to-one." Somewhere in that range is a good time to just say, "I do not need to buy spindle count. I can go for performance and just get the SSD." It is still a trade-off; do you want capacity or do you want performance? Today, the performance answer is SSD and not 15K drives.
I would say, right now, we are in a transition period, just like we were around 100 years ago between horse-and-buggy and cars. There was a period where both were available and both were around, but now, there is a shift happening. Over time, we are going go more and more to SSDs. We have already seen it in the consumer space. It is starting to happen in the enterprise space.
This was first published in December 2012