Part 1: The 3 tiers of the storage cake

Part 1: The 3 tiers of the storage cake

By Craig Wilson, Technical Architect at OCF 

Part 1: The 3 tiers of the storage cake

As hard disc drives have grown in capacity we are presented with an interesting problem. Only a few years ago a petabyte of capacity would require an entire rack of equipment. Indeed, my first project with OCF involved a storage solution that clocked in at 1PB per 45U rack, but with single drive capacity soon to hit 20TB we will be able to house a petabyte of capacity in a single storage shelf. This incredible achievement presents a new problem - hard drive performance is not improving in lockstep with capacity. 

In fact, per TB performance is going down dramatically so hard drive storage is effectively getting slower. 10 years ago, it took 500 hard drives for a single petabyte of storage and now it only takes 50 drives for the same capacity. There has simply not been a 10x increase in hard drive performance in that time. Seagate has set out a roadmap to 120TB HDDs by 2030 and while it has detailed some plans to increase performance with its Mach.2 dual actuator technology the per TB performance will still decrease as capacities increase beyond 30TB. 

Hard drives are no longer the go-to answer

Today you must consider if the capacity you require will provide the expected performance or if smaller capacity drives would be more appropriate which not only increases the rack space required but also the power consumption and in turn the TCO. Hard drives are no longer the go-to answer for large scale storage anymore, but what is? 

We are all aware of the benefits that flash storage brings to the party, you only need to read the marketing material from any of the flash vendors, they clearly believe that flash is the future. The improvements on throughput and IOPs performance is huge when compared to hard drives and unlike hard drives this shows no signs of stopping with PCIe Gen4 NVMe drives now on the market and hitting an incredible 7GBps sequential read performance per drive. Capacities are increasing too, with 15.36TB drives available from Lenovo DE series storage arrays and IBM producing 38.4TB FlashCore modules for the FlashSystem storage arrays that are both available today. With the increase in capacities, we can now get higher capacity density with flash storage than we can with traditional hard drives.

The downside to this of course is price, per TB pricing on flash storage continues to vastly exceed hard drive pricing and an all-flash storage solution can be a huge investment when everyone is under every increasing pressure to maximise the return on investment for any large-scale solution. 

Please join me in my second blog where I will explore the third player in this game….tape, and how by tiering we can improve storage performance to maximise ROI.