Storage trends are always toward faster, higher-capacity systems. This is particularly true of clustered storage, storage area networks and cloud storage. The drive for better performance has even pushed some storage vendors to use huge amounts of expensive random access memory (RAM), with battery backups and other tweaks to substitute for SSDs or hard drives. Now the highest-performance SSDs are coming closer to RAM speeds, at much lower costs.
It’s well-known that SSDs are faster than hard drives; less well-known is that SSDs are becoming so fast that they’re running up against the limits of the interfaces used to connect them to their systems. The fastest SATA interfaces can only get to 6 gigabits per second (Gb/s). Even the SAS interfaces used in servers can only get to 12 Gb/s.
PCIe NVMe: A New Type of SSD
The NVMe PCIe specification is designed to address this issue. NVMe is the physical specification of the new types of SSDs, and PCIe is the interface specification, which uses 1x, 2x or 4x PCIe lanes of the same type used for PCI graphics cards and other add-on cards. A 4x PCIe device can reach speeds of up to 32 Gb/s, much faster than the older types of interfaces. In addition, NVMe drives take up less space and are able to handle up to 64k queue lines, delivering much higher efficiency.
While the higher performance of NVMe PCIe SSDs is useful inside high-performance PCs, it’s even more useful in data center storage systems. The latest storage trends include both NVMe PCIe SSDs as well as general-purpose SSDs, hard disks and even tape in separate storage tiers. Since typical clustered storage systems are being accessed by multiple servers simultaneously, they need the best performance they can get, both in terms of gigabytes per second and in terms of the number of input/output operations per second they can sustain.
Higher Density, Higher Performance
Many storage systems cram as many drives into a small space as possible. The earliest such systems put 42 or more 3.5″ hard drives into a four rack unit (4u) 19″ chassis. Next came 2.5″ drives, which require much less space. NVMe SSDs, with volumes less than a third of a 2.5″ SSD, could fit even more drives in a chassis only one rack unit high. With all that power, there are some trade offs in energy consumption and heating, which means new ways of designing the servers.
Since data center storage systems, including clustered object storage, storage area networks and cloud storage systems, are being accessed by many servers simultaneously, each server normally has one or more queues of storage requests waiting to be serviced by the system. Since NVMe supports 64k (65,536) queues, it can easily handle lots of simultaneous requests.
As storage vendors work out how to handle large groups of NVMe drives, the rest of the groundwork has been laid to create storage systems with radically higher performance and capacity to meet the ever-growing needs of computer networks. Enterprise-class NVMe PCIe SSDs like the Samsung 950 PRO provide huge increases in performance, with lower energy consumption and cooling requirements.
Learn more about the performance benefits of PCIe NVMe SSDs in this white paper
