Now that nearly every storage vendor supports solid-state drives (SSDs) in storage arrays, customers are looking...
for improvements that will spur widespread adoption.
When EMC Corp. CEO Joe Tucci this week said his company is in Phase 2 of development for SSDs, he could have been speaking for the industry in general. If storage experts get their way, the next phase will include automated tiering and sub-logical unit number (LUN) allocation, support for more writes, higher capacity points, and better education and assessment of the appropriate data to put on SSDs. And customers would obviously like to see lower pricing for solid-state drives.
Industry experts expect more vendors to follow Compellent Technologies Inc. and Sun Microsystems Inc. in offering automated management of solid-state capacity along with traditional hard drive capacity.
"SSD looks a lot like dedicated cache in the way it is managed now," Nashua, N.H.-based Illuminata Inc. principal advisor John Webster wrote in an email to SearchStorage.com. "Phase 2, I believe, will be automated tiering with more sophisticated data management in and out of the SSD tier than the caching algorithms that have been used for decades."
Some are leery of this concept, though. "I don't want to burden the storage subsystem with doing that processing and, if everybody does it, each vendor will do it differently," said NetApp and EMC customer Tom Becchetti, who requests that his company not be named. "That kind of thing has to be done at the level of something like VMware or a side management system, not within the storage subsystem."
Becchetti plans to install a RAID group of STEC Inc. SSDs into an EMC Symmetrix DMX disk array. He wants solid-state drive vendors to "make sure they're reliable for much more writes." Currently, enterprise SSDs have a finite number of write cycles -- usually between 100,000 and 300,000 -- they can tolerate before the Flash cells within them wear out.
More granular and sophisticated provisioning is another item on the SSD wish list. Compellent can offer block-level automated storage data migration, but most vendors don't have similar features for SSD capacity.
"Every environment is different—if you have to put a whole LUN on an SSD it might not be granular enough for some users," said Andrew Reichman, senior analyst at Cambridge, Mass.-based Forrester Research Inc. "Access patterns on particular rows in a database can be different within a LUN."
Tom Trainer, founder and analyst at Analytico Inc., said he would like to see thin provisioning for SSDs eventually. "As capacity points increase, [vendors should] add SSDs to the overall thin provisioning mix, further driving their cost effectiveness," he said. "[They should also] add SSD support to the overall platform software mix, [using] snapshots, clones, [and] local and remote replication." EMC already includes solid-state drive capacity in snapshot and replication policies.
Picking the best spots for SSD
But customers have to decide what to use SSDs for before they worry about provisioning and automated tiering. For many considering solid state, this is still a point of some confusion.
"What storage has always struggled with is the ability for an application to predict how much throughput and IOPS it needs—that's never been well defined," said Rodney Willms, senior storage engineer at Sutter Health in Sacramento, Calif. "There should be some education [for users] on where SSDs can fit."
Despite the general difficulty of defining performance needs, Willms said he intends to evaluate SSDs for his next hardware refresh. But others will need more convincing before taking an in-depth look at the technology.
"I'm keeping an eye on the developments there, but as yet haven't come across any compelling reason to deploy in my data center," wrote David Grant, data center manager at Kanata, Ontario-based Mitel Networks Corp., in an email to SearchStorage.com. "They do remain on my list of options should I find an app or service that might benefit from using an SSD instead of a more standard hard drive, but for now they're just an interesting technology option."
Willms said he hopes SSDs will be available in higher capacities when he's ready to buy. Today, the most widely deployed enterprise drives from Intel Corp. are available in 32 GB or 64 GB capacities. STEC and EMC ship 146 GB SSDs. "At a minimum, SSD capacity should take off where 146 gigabyte Fibre Channel drives left off," Willms said. "Anything less than that now in 2009 is absurd."
Cost still a hurdle
Vendors usually point to cost per IOPS when pushing solid-state storage, but some customers still can't get past the cost per gigabyte for SSDs with relatively limited capacity. Although the cost of Flash is coming down, the price per gigabyte for solid state can run from 20 times to 40 times that of traditional hard drives.
"There might be some validity there, but I'm still concerned about the cost-per-gigabyte side," said David Stevens, storage manager for computing services at Pittsburgh-based Carnegie Mellon University. "It's not just raw price that's the issue. It's the price per gigabyte—until it comes down to a similar price point to what's available in hard drives, people aren't going to be willing to use it."