SSDs in the enterprise: It's about more than just speed

They're fast, sure, but they have so much more to offer

Reliability improvements

The acquisition cost of SSDs is still greater than that of HDDs, especially for higher-performance enterprise components which may be over-provisioned to improve reliability. Nevertheless, solid-state storage still brings some surprising improvements in operating costs beyond even space and power savings. Increased reliability is one of them. According to IT Brand Pulse’s Berry, part of the operating advantage of SSDs over HDDs is the reduction in drive crashes. “This is something all IT people hate, are now numb to, and accept - stocking and replacing HDDs as part of their daily life,” he says.

Around six in every ten respondents to IT Brand Pulse’s surveys keep spare hard drives on hand to replace broken ones in servers and disk arrays, which incurs some element of financial and technical risk. HDD technology continues to fall in price and increase in capacity, meaning that the longer you keep a hard drive in inventory, the more of a premium you’re paying for it.

Increasingly, people are turning to SSDs to mitigate that problem, because there are no heads to crash. His survey base said that just over two thirds (67 per cent) of people reduced operating costs by eliminating HDD crashes with solid-state storage.

Increased reliability is a factor with SSDs, for sure, although this comparison to HDD has its nuances. This six-year study of flash SSD use in Google data centres shows that SSDs need replacing far less than HDDs, although the occurrence of uncorrectable errors is higher (meaning that enterprises should back up SSD data more).

The fact remains that the nature of SSDs makes preventative maintenance far easier, says Niebel. “It’s easier to administer in terms of knowing when the drive will fail and being able to remove the drive and hot swap it effectively,” he says.

Administration is a significant factor in the operating cost of a drive, points out IT Brand Pulse’s Berry. The application wants a certain number of IOPs, and IT teams will need to do a complex configuration dance to satisfy it with hard drive-based arrays. His research shows that over half of IT admins mix different types of disk in their arrays to find a balance between performance, capacity and reliability.

“Storage admins have to set up and maintain caches, LUNs and mixes of drive speeds to maintain application performance,” he says. “With SSD, all I/O is fast without tuning.”

So, should enterprises adopt SSDs, and where? Benefits outside performance may look good on paper, but it doesn’t necessarily impact buying decisions as much as some might think. “Although SSD makers talk a lot about space and power savings, these aren’t big motivators for the buyers,” said Jim Handy, general director at Objective Analysis, which conducts semiconductor market research.

For many, it may make sense to take a moderate approach, buying hybrid systems that give them targeted power where they need it, warns Handy. “Full SSD approaches really clobber I/O performance issues, but the approach can be wasteful from a cost standpoint,” Handy says. Instead, applying HDD/SSD combinations can enable buyers to apply solid state more judiciously, in areas such as metadata storage and processing, say. Whereas the configuration challenges are minimal on all-flash arrays, though, hybrid storage architectures take more work. “Users have to have a very good understanding of their workloads to be able to optimize their HDD/SSD balance for the best cost/performance,” Handy warns.

Coming next

What can we expect next in enterprise SSDs? They will attack both super-high performance use cases and more cost-related ones, say experts. Storage analyst Zsolt Kerekes, founder of StorageSearch.com, believes that volatile DRAM will be one of the next areas to fall to SSDs.

“The reason that SSDs will shrink the DRAM market is due to fixing application architecture problems which have piled up over decades,” he says, highlighting latency issues with DRAM. While DRAM’s price has fallen considerably, its latency remains relatively high, which is a problem as CPUs get faster. “These problems were too expensive for any one company to solve. It needed an SSD-dominated ecosystem to make the investments in software worthwhile.”

Solid state’s appeal in this area will be doubtless enhanced by XPoint, the non-volatile memory architecture announced by Intel and Micron that promises more durability and faster operating speeds.

DRAM replacement is still a high-performance application, but there is action for SSDs elsewhere in the enterprise. Alex McDonald, board member at SNIA Europe, believes that the industry will gradually expand its use of this technology beyond performance-focused applications in the longer term.

“General purpose storage will follow, as the price of SSD falls nearer HDD, capacities increase, and as increasing power costs make simply spinning HDDs uneconomic,” he says. “In other words, not performance based; the driver, in the long run, will be about economics and the dollar-per-bit cost.” The applications themselves will be immaterial in this second wave of adoption, he adds.

SSD may even find a place in bulk storage, say experts. WebFeet Research’s Niebel highlights hyperscale data processors such as social networking firms that will want access to data on their users going back years, and may not necessarily want to store it on very slow tape storage or on power-hungry hard drives. Massive Arrays of Idle Disks (MAIDS) are one approach here, but low-cost, relatively slow SSDs are another.

“We want to analyze historical data and store more of it first from tape to hard drives and then solid state storage which can be addressed through 3D NAND flash where we get the price per Gb down to 5 cents,” he says. SSDs have lots of benefits – and huge potential – outside pure speed. Getting the market to understand that and take advantage of the TCO benefits they offer will be an exercise in education. It’s the one area of solid state storage where a bit of fast spin may actually be beneficial. ®