Friday, April 27, 2018

Why SATA flash drives are being left in the dust

The SATA interface on SSDs was a marriage of convenience, not love. Flash SSDs are so fast that SATA simply can't keep up. But NVMe can, and that is changing how systems are configured and infrastructures are designed.



I noted years ago that if the flash had been available in 1956 - the year the first disk drive shipped - we would never be building SSDs with SATA interfaces today. SATA works well for disks because disks are slow.

SATA responded by upping their data rates from a raw 3 Gb/sec to 6 Gb/sec. But bandwidth wasn't the problem - IOPS and latency were.

While drive vendors will continue to produce SATA SSDs for cost-sensitive users, the real action today is in NVMe SSDs. These are extremely high-performance SSDs that provide hundreds of thousands of IOPS, gigabytes per second, and extremely low latency. Performance that only a few years ago required $100,000++ storage array.

CASE STUDIES

Most customers are loath to share the secrets of their configuration choices, rightfully considering them trade secrets in an intensely competitive environment. But I recently spoke to a Kingston Technology senior systems engineer, Cameron Crandall, about customer deployments that showed how NVMe SSDs are changing how people configure systems and manage their workflows.

Kingston is the storage industry's best-kept secret. They are a privately held, $6.6 billion US company. Started by a couple of engineers in the late 80s, they focus on well-engineered products rather than marketing. Which may explain why they have a 59 percent add-on server memory share - not counting their OEM business. Color me impressed.

Kingston also makes NVMe SSDs. That's where my discussion with Cameron came in.

LARGE WEB HOST

Cameron described a large web hosting company that, for performance reasons, used an internal PCIe RAID controller on web caching servers. Behind the RAID controller, they had configured four SATA SSDs to achieve their capacity and bandwidth goals.

While it worked, that configuration was a setup and management hassle. Five components meant more frequent system slowdowns - when drives failed - and maintenance headaches.

Replacing that with a single NVMe SSD, they were able to remove the RAID controller and four SATA SSDs from every configuration. That change alone meant much less need to open servers.

Not only did the customer get a much simpler configuration, but they also got higher performance and lower latency. Since they replaced five devices with one, a Kingston DCP1000, with an 800,000 hour MTBF, and up to 3.2TB of capacity, their subsystem reliability is considerably better, improving uptime.

HOLLYWOOD STUDIO

While 4K is all the rage in home video, Hollywood is starting to transition to shooting in 8k to help future-proof their content. But 8k video files are 4x the size of the 4K video, which creates a serious problem for the digital techs charged with preserving, moving, and sharing these files.

One large studio Cameron works with faced the issue of moving 2-3 Terabytes of 8k data between the production site and the post-production facility, twice a day! No network could handle this fast enough, so the studio opted to copy the data to transportable NVMe/PCIe drives.

The studio estimates that using the NVMe drives saves the camera operator about an hour a day, waiting for the data to copy. But the big win is that at least 10 people are waiting to access the footage, and getting it an hour sooner translates to real savings for the production, as well as the faster turnaround.

So these NVMe drives have replaced portable storage arrays, and networks - even 10Gb Ethernet - for moving data rapidly. Note, the studio used prototype drives from Kingston for testing, but we can expect to see them generally available later this year.

THE STORAGE BITS TAKE

System configuration is a constant game of one-upmanship between CPU, interconnects, and storage. Faster CPUs - which have been thin on the ground lately - chew up data faster, requiring more bandwidth and IOPS.

Faster interconnects, such as 12 Gb/sec SAS, provide more bandwidth, but once the storage can provide lots of IOPS, bandwidth becomes secondary to latency for most workloads. It is an ever-evolving merry-go-round - and good news for everyone who relies on computers.

NVMe SSDs are already making a mark in prosumer notebooks, where Apple has been a leader. But SATA's low cost will keep it in the game for price-sensitive users.

With the continued growth of edge computing, the real win is in the cloud, whose massive warehouse-sized computers make out smartphones smart, and whose smooth operation and high-performance pay dividends for billions of users.


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