The pros and cons of enterprise flash storage

We hear more and more about flash these days, but replacing disk-based arrays with SSDs is not a decision to be taken lightly

Solid-state storage is not a particularly new technology, indeed it is decades old, but recently we have started to hear more and more about it as a wider range of companies discover they need very rapid reads and writes, largely because of the advance of virtualisation.

Many are beefing up their servers with flash memory to improve their performance, while others are replacing spinning media in storage arrays with flash to increase the input/output per second (IOPs). Flash arrays also promise lower power consumption, lower latency and a smaller physical footprint than their physical counterparts.

However, simply turfing out the old and bringing in the new will not necessarily improve performance in the ways expected. There are many compatibility issues to consider, such as how the flash array will co-exist with existing infrastructure and virtualisation software. To get optimum storage performance also requires consideration of data tiering, caching and compression technologies. It is hardly plug-and-play.

Then there is the question of cost-benefit. Flash is more expensive than the disk-based equivalent, often significantly so, and you need to make sure you select the right type of array for the task at hand. There is no point in forking out for a top-end all-flash array if your needs for throughput and low latency are modest and likely to remain so.

In fact there is a confusing range of flash options to choose from ranging from all-flash arrays, through hybrid systems which blend bulk storage capacity on disk with a flash caching system, to converged systems which promise all-flash performance at a lower price.

A Computing survey of 100 IT data centre managers and operatives found that among large companies all these options were running neck and neck, while in smaller ones hybrid flash arrays were much more popular.

Asked about their motivation for choosing flash, respondents unsurprisingly ranked high IOPs top of the list, while scalability, another touted benefit of flash, only achieved a middling ranking.

Among the drawbacks of flash were thought to be its cost, confusion about the options and worries about its longevity. Flash arrays typically do not last as long as their disk-based counterparts - yet another reason why potential buyers need to consider their use cases and future plans carefully before they invest.

Computing will be hosting a web seminar entitled When flash makes sense: dos and don'ts of flash storage on 19 May during which more of the research findings will be discussed. Register now and put your flash questions to our expert panellists, either before the event or on the day.