Why flash storage may not be right for you

The golden triangle: speed, cost and reliability

What customers want at the moment is all about flash SSD drives. The high speed, dazzling performance of flash is a big attraction to any organisation looking for better performance in its datacentre.

But for many companies, this won't be the final option, primarily because it doesn't satisfy all three of the golden triangle of requirements: speed, cost and reliability. Let's look at this in more detail:

The cost of speed

The cost of SSDs is still prohibitive to many companies. In a networked RAID system, speed can be increased through the choice of drive type, which ranges from low-cost 7k rpm HDDs (7k SAS costing around $0.33 per GB), through to 10k/15k drives at about $0.70 per GB and then, at the top end, SSD/flash drives which cost perhaps ten times more than a hard disk drive currently at $12.21 per GB for the equivalent capacities.

Each customer has different priorities regarding storage speed, and although performance is crucial where it directly has an impact on productivity, the general rule of thumb is that the storage infrastructure should be able to cope with the peak traffic workload while still providing acceptable response times for all applications.

Sensible allocation of resources

For most companies it makes little sense to store all of their data on costly SSDs. In practice, savvy organisations place their most used and critical applications on flash with the rest on other storage media such as HDDs and tape.

When looking at the all-flash networked RAID arrays, customers need to consider how much of their data really needs SSD levels of performance.

Although the all-flash systems will provide very low latency access times, there is a point quite early on where adding more SSD drives will not provide further increases in data throughput, as the SSD performance will quickly saturate the bandwidth of the RAID controllers.

So for many customers, a hybrid approach combining both SSD and HDD with intelligent real-time auto-tiering is gaining popularity.

Risk and reliability

In reality, what often happens is that many customers choose the lowest cost RAID system they can find based on the theory that RAID protection will save them from data loss. However, in the event of a disaster, the less proven RAID software will often fail to deliver the goods.

Subject to a lot of debate right now regarding its efficiency, RAID is data protection but not back up, which means that the possibility of losing data should the RAID controllers fail is high.

Compromise for the golden triangle

More often than not, customers compromise and adopt a tiered approach for managing their data in the most cost effective way and on the most suitable disk drives for the various types of data they have.

This is just as well as, according to analysts, there are simply not enough SSD production facilities should all large storage users decide to disregard their existing disks for flash!

And so the golden triangle of speed, cost and reliability tends to be delivered with a combined media approach and compromise wins through. The job for the industry in 2014 is to continue to help find the best golden triangle outcome for each customer.

  • Warren Reid is Director of Marketing at Dot Hill Systems and has responsibility for marketing both through and to Dot Hill's partners in the EMEA region.