How to have your cake and eat it too
Storage administrators for years have been faced with a daunting choice: stick with hard disk drives (HDDs), which are optimized for high density and maximum capacity, or go for flash-based infrastructures, which feature increased speed and performance but are wanting in capacity. It seems, however, that the administrators can now not only have their cake, but they can eat it, too! And with the advent of the new shingled-magnetic recording (SMR) technology, they are finding that that cake is layered.
As external analyst George Crump, founder of Storage Switzerland, writes in his article “Flash + SMR = Storage Density and Performance,”the answer has arrived in the form of hybrid flash-SMR HDD storage infrastructures.
Dramatically increased capacities
SMR is a new hard drive technology that can lead to dramatic increases in HDD maximum capacities by allowing the tracks on a hard drive platter to be partially layered atop one another, much like the tiles on a shingled roof. Most HDDs use a more conventional parallel track layout, where each track is laid out fully exposed alongside other fully exposed adjacent tracks. The effect of overlapping is that more tracks can fit in the same amount of space than if the tracks were laid out using the non-overlapping arrangement.
SMR technology currently allows for an increase in capacity of approximately 35 percent over conventional drives. And given that the form factor of SMR HDDs is the same as that of conventional HDDs, this would mean, for example, that an 8TB SMR HDD would use the same amount of material and have the same footprint as a regular 6TB HDD. The technology has tremendous potential for even greater gains.
By themselves, however, SMR drives aren’t the Holy Grail for today’s storage needs.
Maximizing I/Os
As a complementary technology, flash drives handle random I/Os particularly well. The hybrid architecture that Crump describes can handle random I/Os as quickly as a flash system but has the increased capacity of a state-of-the-art SMR HDD system. The hybrid strategy is simple: Use SMR HDD technology to maximize capacity of existing data centers and store persistent data, but use flash drives with the right software to handle the random I/Os.
“If flash storage is combined with the right software, it can act as a ‘shock absorber’ to the SMR drives,” Crump writes, “enabling data centers to rapidly adopt solidly performing, but highly dense storage infrastructures, which will expand the use cases.”
In other words, by combining flash drives with HDDs in a hybrid storage system, we have can have capacity to store whatever we want and the speed to access it at the fastest possible rates.
