Flash storage may live up to its name, but there is always room for speed improvement, especially in data centers. In the never-ending quest for faster storage performance, enterprises are adopting NVMe, a flash-friendly technology that accelerates solid-state drive (SSDs) performance and the storage workloads they encounter. What does that mean for SATA?
Let’s take a look at both NVMe and SATA and analyze what data storage professionals 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.
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.”
If you’re in the market for the best SSDs, see our list of the best and fastest SSDs.
NVMe solves a problem that occurs when fast flash-based storage collides with legacy data transport technologies: bottlenecking.
Essentially, an NVMe drive 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. Its connection through PCIe brings data storage into main memory for processing, without passing through a controller.
Performance-wise, NVMe is a game-changer. But it doesn’t necessarily guarantee 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 NVMe drives are a good fit for their IT objectives and infrastructure. They may find other factors are bottlenecking applications and affecting performance.
NVMe SSDs are also known as PCIe SSDs, referencing their connection to the PCIe bus. They 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.
Recently, talk has arisen of utilizing NVMe protocols for HDDs, providing added performance in data centers. Though this is a relatively new proposition, it suggests that NVMe might be able to provide more flexibility for data center hardware in the future.
M.2 and NVMe
M.2 is a term frequently used in conjunction with SSDs and NVMe. M.2 is a form factor rather than a protocol, which NVMe and SATA are. An M.2 NVMe SSD fits under the motherboard of a computer, slotting in rather than being connected by an external cable. An M.2 drive is the most common form factor for NVMe SSDs; it’s small and lightweight. M.2 SATA drives can also exist, but M.2 NVMe drives are much more well known.
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, which are easier to handle. SATA significantly improves upon its predecessor, PATA (Parallel ATA).
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 includes SATA Express. SATA Express supports connections to both SATA and PCIe in its connector specification (it’s not to be confused with eSATA or External Serial Advanced Technology Attachment). It is designed to reach speeds of 1,969 MB/s. It didn’t catch on in the tech industry, though, despite its promising data transfer capabilities. The development of smaller, less bulky M.2 form factors, some of which can also support PCIe, rendered them slightly less helpful.
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.
NVMe vs. SATA
Performance
Top SATA SSD read speeds are 600 MB/s, but that’s the overhead limit in an ideal situation. Current SATA III speeds typically fall a little bit or significantly under 600.
NVMe SSD top read speeds center somewhere between 3,500-5,000 MB/s. Samsung, one of the frontrunners in SSD production, offers the 970 Evo Plus, which tops out around 3,500 MB/s sequential read speed and 3,300 MB/s sequential write speed. The Evo Plus has edged out the Samsung 970 Pro in performance, though the Pro is still a strong choice. Also, there are some NVMe drives, like the Samsung 980 PRO, that can reach around 7,000 MB/s under ideal conditions. However, this isn’t a rate that buyers should rely on for ordinary operations. Top rates are benchmarked in very specific test situations.
Price
Both SATA and NVMe prices have dropped over the past few years. A 512-GB Samsung 860 Pro SATA SSD costs about $100, while a 512-GB Samsung 970 Pro NVMe SSD costs approximately $160.
Prices for both SSDs vary greatly depending on size and capacity, and overall, a SATA SSD is still more affordable. For extremely high-performance needs, NVMe may be the better enterprise choice, and the tech industry increasingly utilizes NVMe. SATA is by no means obsolete, and it’s useful for storage and gaming purposes; SSDs are still incredibly fast compared to HDDs. They’re also long-established, and older machines that may not support NVMe devices will still support SATA drives.
Enterprise SSDs are an entirely different story; prices vary, to put it mildly, but typically run well into the hundreds and can run into the thousands. Some NVMe drives will be more expensive than SATA, but often prices compare rather evenly here.
Parallelism
NVMe’s parallelism refers to its ability to run many operations at once through multiple threads. NVMe’s rapid I/O greatly increases its processing speeds. NVMe drives typically have a queue depth of 64,000 and support for 64K queues as well. SATA makes do with a queue depth of 32 and a single command queue; 32 I/O requests are the maximum the drive can hold in queue at any time.
| 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 or SATA?
Both have their uses and advantages. SATA’s primary advantage is its lower prices, but as NVMe prices also decrease, businesses may find that the faster SSD is worth the extra expense. The true benefit to investing in an SATA drive, then, is that older computers are more likely to support it. Some computers still don’t have PCIe buses, nor do some yet support NVMe. Some data centers may find that using older technology like SATA still works for them.
Additionally, smaller enterprises that haven’t yet budgeted for an NVMe SSD — and still have SATA SSDs that work well — may find that keeping their current drives is the better bet for now. An NVMe device is not a magical fix for all enterprises.
NVMe is ideal for high performance data processing and large amounts of stored data. 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.
NVMe will coexist with SATA, as well as SAS (Serial Attached SCSI) devices, within data center environments for the foreseeable future.
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.
NVMe over Fabrics
One developing instance of NVMe extends to entire networks rather than just one computer. NVMe over Fabrics (NVMe-oF) allows stored data processing across Ethernet and Fibre Channel networks. Parallel I/O technology manages input and output requests on an NVMe network so that multiple requests can be processed at once instead of queueing, similarly to NVMe storage on just one computer. NVMe-oF widens NVMe storage to more than just one application.
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