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For some businesses, the hybrid storage array offers the best of both worlds. In comparison to the all-flash array – clearly the highest performance option – a hybrid array allows a lower cost, yet also enables some impressive performance. It's the classic "transitional" storage solution as flash becomes ever more dominant in storage infrastructures, yet hard disk drives remain abundant.
Yet for all its advantages, a hybrid storage array isn't the automatic choice. Let's explore the hybrid vs. all-flash array question.
Factors that Weigh Against Choosing a Hybrid Storage Array
Despite the huge up front cost differential between a hybrid storage solution and an all-flash array, there are still strong arguments in favor of organizations buying all-flash arrays even when they do not currently operate high transaction environments or run applications that require very high storage performance.
To understand why, it's useful to remember that the up-front cost of a storage array is typically around 20% of the total cost of ownership of the array over a period of about three years.
Other costs include:
- Power and cooling costs. For a storage array these can be significant. But all-flash arrays have a significant OpEX advantage over hybrid storage solutions in this regard because their power and cooling requirements are much lower.
- Management costs. There are significant costs associated with managing conventional HDD and hybrid storage systems, and in particular ensuring that performance characteristics meet application requirements. This is far from straightforward when dealing with HDDs, because performance, as mentioned above, can be unpredictable.
In other words, it is important to really think about whether hybrid drives are worth it. "We see diagnosing (performance) issues as a key trend," says Sinclair. "If you plug in an all-flash array then those issues just go away and you could free up two or three people."
He adds that with an all-flash array, SQL queries could take 1/10th of the time that they do with a disk-based array, which means that database administrators can spend less time trying to generate more efficient queries and do something more productive instead. That's important when making a hybrid v flash array comparison.
Another argument against hybrid storage solutions is that they are likely to be less reliable, according to Sinclair. That's because, as capacity scales, there are more, higher capacity disks in the array. That means that failures become more common and rebuilds take longer. "At a certain point it seems that there are always failures, and rebuilds are always taking place, impacting performance," he points out.
When NOT to Use Hybrid Storage Solutions
The unreliability of large arrays of HDDs in a hybrid array means that there is a good argument not to use them for manageability reasons alone, according to Sinclair. "Managing the chaos drives people to all-flash arrays just as much as getting apps to run faster: people just want to remove a headache."
But for some organizations there is a much more compelling reason not to use hybrid arrays, and to move to all-flash arrays instead: the hidden "opportunity cost" of using hybrid storage solutions which is often excluded from the decision-making process when considering if hybrid drives are worth it or examining flash storage pros and cons.
To appreciate the opportunity cost argument, it's vital to remember that organizations of all sizes are storing more data than ever before. More importantly, many organizations are not just storing more data but also extracting value from that stored data using low cost data analytics apps.
"What we are seeing is that some businesses understand that they are digital businesses, and that they need to leverage their data because their data is an asset," says Sinclair.
He adds that companies that just see IT as a cost center are more likely to buy hybrid arrays because the up-front cost is lower. But "digital businesses" can unlock huge value from their data through analytics – if they spend a little more up front on all-flash arrays to make their data more quickly accessible. "Companies like this understand that they need to deploy the right infrastructure to maximize the potential of the data that they own," Sinclair says.
Ultimately, the right storage system for one organization may not be the optimum solution for another, as HDD, hybrid and all-flash arrays all have their pros and cons. But as the price of flash-based storage continues to decline, the benefits of fast persistent storage in hybrid or all-flash arrays are becoming increasingly accessible to everyone.