Taking the hybrid route


7 April 2015
Mak Chin Wah of Dell

As the data centre continues to evolve, the rapid adoption of enterprise flash storage today is helping organisations contend with business demands to store and access a growing amount of applications and digital data at rates faster than ever. According to IDC, more and more flash-based storage is being used in data centres to deliver enterprise-class data services, including snapshots, clones, encryption, replication, quality of service and storage efficiency.

Flash solid state drives (SSDs) improve the latency or speed of access to stored applications and data. The two key architectures in enterprise flash storage arrays are all-flash and hybrid arrays.

All-flash arrays contain no traditional, rotational spinning disk storage, and all data is stored on solid state drives (SSD). Since SSDs offer massive performance with relatively low capacity, all-flash arrays often use data reduction technologies such as compression and deduplication that lead to lower price per GB. This is attractive to customers looking for faster storage performance.

However, despite recent cost dips, the all-flash storage price point often deters customers away from going this route. In the vast majority of use cases, IT leaders want the ability to leverage flash, but they also want an even more affordable lower tier for storing cold data.

Hybrid flash arrays

Hybrid flash storage offers the best of both worlds: High performance flash for fastest performance with the most frequently accessed and highest demanding applications, and low cost bulk storage for aging, or colder, data.  While some workloads call for race car speeds at all times, more often than not, an organisation has needs for supporting both high performance applications and less accessed data, which doesn’t require expensive storage. This is why most organisations can benefit from a single SAN that handles both ends of the spectrum at the same time.

IDC reported that the market for hybrid-flash array reached $10 billion in 2014, while all-flash arrays reached $1.3 billion. This gap will remain in the future as more storage buyers are choosing hybrid flash storage arrays over all-flash arrays. According to a 2014 IDC survey of companies with more than 1,000 employees, 51.5 per cent of respondents currently are using flash in their external disk storage environment, but only 7 per cent of this group - around 3.5 per cent of all surveyed - are using an all-flash array deployment model. By 2016, all-flash arrays are expected to remain around only 10 per cent of the combined hybrid-flash and all-flash array market.

The best hybrid arrays optimise costs by offering customers the flexibility of supporting all-flash or a hybrid mix of drive types, managed autonomously, and providing optimal economics for customers’ varied workloads.

While many available flash arrays leverage write-intensive SSD drives, a balance of write-intensive and read-intensive SSD drives offers customers greater overall cost for performance. Overall flash reliability is increased when an array leverages the less expensive read-intensive flash tier mostly for reads. Capacity of the more expensive write-intensive tier can be kept to a minimum, just large enough to handle inbound write traffic. As a result, arrays that can leverage this model dramatically reduce the overall cost to implement flash to a price point equal to or even better than traditional spinning disk.

While HDDs might be slower, they serve an important purpose of reducing total storage costs through greater capacity and lower drive costs. Expect to see a continued increase in the most affordable 7.25K RPM drives, which are becoming solidified as the lowest data tier.

With the combination of SSD drive types and HDDs, customers are finding the best mix of price for performance. To take advantage of flash performance and make the most out of an IT budget, the hybrid approach makes the most practical sense.

Mak Chin Wah is general manager, Enterprise Solutions, Dell South Asia.