Flash storage can sure live up to its name, but there's always room for speed improvements, particularly in the data center.
In the never-ending quest for faster storage performance, enterprises are warming to NVME, a flash-friendly technology that supercharges solid-state drives (SSDs) and the storage workloads they encounter. What does that mean for SATA?
Let's take a look at the NVMe vs SATA debate in terms of what storage pros need to know.
What is NVMe?
Short for NVM Express or Non-Volatile Memory Express, NVME is a host controller interface specification that uses the PCI Express (PCIe) bus to connect SSDs to a server. The technology was developed by NVM Express, Inc., a non-profit industry association backed by leading IT companies and storage providers, including Cisco, Dell, NetApp, Seagate and Western Digital.http://o1.qnsr.com/log/p.gif?;n=203;c=204655439;s=10655;x=7936;f=201806121855330;u=j;z=TIMESTAMP;a=20400368;e=i
NVM Express, Inc. explains:
"The interface provides an optimized command issue and completion path. It includes support for parallel operation by supporting up to 64K commands within a single I/O queue to the device. Additionally, support has been added for many Enterprise capabilities like end-to-end data protection (compatible with T10 DIF [Data Integrity Field] and DIX [Data Integrity Extension] standards), enhanced error reporting, and virtualization."
NVMe solves a problem that occurs when fast flash-based storage collides with legacy data transport technologies: bottlenecking.
Essentially, SSDs can outperform the storage interfaces and bus architectures that were designed for spinning disks. Keeping servers with powerful, multicore processors and heaps of RAM waiting for data isn't exactly a prudent use of one's IT investments.
NVMe to the rescue. It can pump data at breakneck rates compared to SATA and at lower latency, providing brisk performance and enabling businesses to tackle demanding storage workloads that may have given them pause in the past.
Performance-wise, NVMe is a game-changer but it's no guarantee of faster flash performance. Before taking the plunge, storage managers will want to do their homework and kick the tires on the technology to ensure that it's a good fit for their IT objectives. They may find other factors are bottlenecking applications and affecting performance.
NVMe SSDs are available from a number of vendors, including Intel, Micron, Samsung and Western Digital. Installation options include M.2 and 2.5-inch U.2, and of course, PCIe cards.
What is SATA?
SATA or Serial ATA, itself shortened from Serial Advanced Technology Attachment, is a successor to the Parallel ATA bus interface used to connect SSDs, hard disk drives (HDDs) and optical drives. Anyone who has tinkered around computers long enough will remember the flat and wide ribbon-like cables used in PATA connections compared to the thin SATA cables that are easier to handle.
But there's more to the SATA story besides neater, more manageable cabling.
Since SATA hit the scene in 2000, the standard has undergone a number of performance-enhancing revisions. For example, SATA I or 1.0, is capable of transferring data at a rate of up to 150 MB/s (megabytes per second). SATA III can hit speeds of up to 600 MB/s.
Then there's revision 3.2, introduced in 2013, which supports both SATA and PCIe in the SATA Express connector specification-not to be confused with eSATA or External Serial Advanced Technology Attachment-and is designed to reach speeds of 1,969 MB/s. While impressive on paper, the industry has largely skipped over SATA Express.
SATA also enables hot plug support, meaning a SATA storage device can be plugged into or removed from a system that is powered on and still operate normally, something that is not possible with its predecessor, PATA. It also uses the Advanced Host Controller Interface (AHCI) interface, which allows for native command queuing (NCQ), a drive optimization technology that improves performance, and the hot plug functionality mentioned earlier.
The standard is maintained by SATA-IO, or the Serial ATA International Organization, a nonprofit formed in 2004. Supporters include AMD, Dell, HPE, Intel, Micron, Seagate and scores of other major IT firms.
How NVMe and SATA Differ
Behind these storage acronyms lie significant differences, which are helping to reshape the enterprise data storage landscape.
- NVME: Only flash need apply
Traditional HDDs are out of luck. With their spinning platters and the drive heads that sweep across them to gather and deposit all those ones and zeroes, mechanical disks are simply too sluggish for the flash-optimized interface. SATA, meanwhile, can accommodate both SSDs and HDDs.
- Leagues apart in performance
SATA SSDs may boast blazing storage performance compared to their HDD cousins, but NVME SSDs can smoke them both by a wide margin.
Remember, SATA III tops out at 600 MB/s, although SSDs attached to this interface generally don't achieve that level of data throughput. A 7,200 RPM SATA hard drive will be lucky to hit a fraction of that, puttering along at 100 MB/s.
Recently, Samsung unveiled consumer-grade NVMe SSDs, the Samsung 970 PRO NVMe and 970 EVO NVMe. Both were able to reach read speeds of up to 3,500 MB/s in tests. When it came to writing data to the SSDs, the 970 PRO edged out the 970 EVO, with speeds of 2,700 MB/s and 2,500 MB/s, respectively.
- Advantageous parallels
Another trait that defines NVMe is its parallelism. As noted at the beginning of the article, NVMe has a queue depth, or commands per queue capacity of 64K, not to mention support for a whopping 64K queues. SATA makes do with a queue depth of 32 and a single command queue.
By enabling vast amounts of IO [input output] operations over a PCIe bus's lanes in parallel, this approach lends itself well to multicore processing, reducing bottlenecks and keeping data flowing into and out of modern day CPUs. On the storage side of the fence, it dovetails with flash's aptitude for random access operations, resulting in fast performance overall.
- SATA is enduring, economical
SATA is well established and it doesn't look like it's going away anytime soon.
SSD and HDD makers both continue to support the standard with higher-capacity drives as the years roll on. They're also generally cheaper than NVMe.
Finally, NVMe can be overkill. Apart from business-critical applications and transaction-heavy databases, users may have a hard time justifying the cost of NVMe for applications that can't hope to exploit the technology's high-performance capabilities. That said, NVMe prices have been known to dip into SATA territory, of late.
NVMe SATA Interface Used in flash environments only Accomodates both SSD and HDD Performance Queue depth capacity of 64k per command
and support for 64k queues
Queue dept capacity of 32
and single command queue
Use Case Good for business-critical applications and transaction-heavy databases Good for high capacity, low availability, and sequential reads Cost Higher cost, but price is decreasing Generally less expensive than NVMe
NVMe and SATA price parity?
While NVMe continues to drop in price, sometimes giving SATA SSDs a run for their money, SATA SSDs often come out on top.
Take the Samsung 970 PRO NVMe example from earlier. The 512 GB version of the consumer-grade SSD retails for $249.99 while the well-regarded Samsung 860 Pro 2.5-inch SATA SSD can be had for $214.99, as of this writing. Users whose systems can't make most out of Samsung's NVMe SSD are likely better off with saving some money with the SATA SSD.
As IT buyers know, moving up to enterprise-class SSDs is a another playing field and prices can be all over the map. Often, their true cost is obscured by the fact that they included as part of a system configuration. Regardless, businesses should be prepared to pay thousands of dollars for a multi-terabyte NVMe drive and somewhat less for the same capacity in a SATA SSD, give or take some terabytes.
Despite this, the NVMe price premium is eroding, a good harbinger for enterprises hoping to eke out blistering performance out of their storage.
NVMe or SATA?
Clearly, technologies that make quick work out of enterprise storage workloads will find fans among today's data center operators. Organizations seeking faster, more responsive application and database performance will want to keep an eye on the market for NVMe-enabled systems.
But don't count SATA out.
NVMe is expected to coexist with SATA, as well as SAS (Serial Attached SCSI) devices, within data center environments for the foreseeable future. It comes down to implementing a tiered storage strategy, where a storage device's cost and performance characteristics are aligned with the value of the data that is placed on it.
Looking ahead, there are other signs that storage vendors are looking to further widen the performance gulf between NVMe and SATA. Intel is a good example. Although it sells flash-based NVMe SSDs, the chipmaker has also brought NVMe Optane SSDs to market.
Optane, based on the company's 3D XPoint technology, is a persistent memory or storage-class memory (SCM) solution that blends the performance characteristics of dynamic random-access memory (DRAM) with flash's ability to retain data when the power is cut off. 3D XPoint was jointly developed by Intel and Micron.
And then there's NVMe over Fabrics (NVMeoF) protocol that enables ultra-low latency storage services from an NVMe SSD outside of a server, over Ethernet, Fibre Channel and InfiniBand networks, blurring the line between internal and external storage. Clearly, the NVMe market will speeding ahead – in more ways than one – in the years ahead.