IT pros are always skeptical about new technology. Is it surprising that flash SSD’s are getting the gimlet eye?
The big worry seems to be endurance. Nobody wants to buy an expensive SSD and have it fail after a year on the job.
But IT infrastructures are designed to manage endurance failures. LTO tape, for example, is specified for a few hundred head passes. Yet tape is the paragon of data persistence.
Hard drive failure rates aren’t low enough for any of us to consider storing important data on one without backup. So why are IT pros so skittish about flash SSD’s?
Or rather, lack of experience. Flash SSDs are evolving rapidly, with new generations arriving every 12 to 18 months.
It takes time for experience with new models to percolate. In the meantime, bad experiences with earlier generation drives continue to circulate.
Vendor secrecy about failure rates and modes doesn’t help. Until the Bianca Schroeder/Google/CMU disk drive studies were released 4 years ago, we had no independent large-scale reliability data.
I hope it won’t take 20 years before we get that information on SSD’s. How about it, vendors?
SSD’s may turn out to be more reliable than hard drives but I won’t believe it until I see independent data. The lack of moving parts is a plus but about half the failures and this drives come from the electronics not the spinning bits. SSDs have most of the same electronics.
SSD equivalent of a head disk assembly
Plane failures are a major trouble spot. Each die consists of two planes. These planes are prone to sudden failure, wiping out half the data on a die.
Most chip carriers contain multiple stacked dies, so a plane failure will remove anywhere from a quarter to an eighth of the chip’s total storage. Most flash controllers lay out the data in ways similar to a RAID array to guard against data loss.
What to look for
Since Maxtor’s well-deserved demise we’ve had reasonable parity between disk drives and disk drive vendors. But that is not the case with the still maturing flash drive market.
Storage Newsletter recently published a list of 85 SSD vendors, most of whom none of us have heard of. Many are focused on the embedded systems market, but also because the SSD market barriers to entry are small: buy controller chip; buy flash on the spot market; gen up a PC board and voilà you are in the SSD market.
But flash that ends up on the spot market at rock-bottom prices is often marginal. The big buyers, like Apple, get first dibs on the best.
SSDs made with spot-market flash and a no-name – USB thumb drive? – controller will have a lot more problems. Which is to say that in today’s SSD market brandnames count.
Other things to look for are a guarantee of total write capacity. Another is a statement on the amount of over provisioning the drive has.
Even better: a five-year guarantee such as Seagate popularized with disks and that Intel just started offering on one of its SSD lines.
The StorageMojo take
I have been as skeptical as anyone on SSDs – read some of my earliest posts – but the time for skepticism has passed. Of course, perform careful evals on any new IT product. But the best flash SSD’s are ready for the enterprise today.
And here’s an even more radical conclusion: the best consumer SSD’s are ready for the enterprise as well. Using any SATA drives in your enterprise?
The key: how is the SSD architected into the system? If it is storage tier the data has to be protected just like a RAID array. If it is a cache you have more flexibility – as long as the data is also on disk.
Yes, it’s more difficult to separate the wheat from the chaff in the SSD market today. But there are quality products available today.
Courteous comments welcome, of course.
Started thinking about this is result of the research project I did a few months ago. Leading-edge storage managers with workloads that would benefit enormously by flash SSD’s weren’t seriously evaluating them today. Big surprise. What do you think?