Eric Shanks of IT Hollow comments:
Consider what would happen if you could see analytics about your workloads to see cache hit ratios. This is something that several vendors can show now including Coho and Cloud Physics. You can now decide to buy more flash based off of how much a workload will benefit from it. Buying additional flash that isn’t large enough for your working set won’t provide you much value. For an example, take a look at the crude diagram below. You can see that you’ll gain larger benefits from flash if you buy 50 GBs of flash vs only 45 GBs due to the working sets. Alternatively going from 20GBs to 40GBs gives you almost no performance benefit at all due to the size of this working set.
Eric takes a look at the hybrid vs. all-flash storage array debate. Including some math from Storage Field Day 6.
Read more at: Will All New Storage Arrays be Hybrid?