You know SSDs - the fast expensive beast that promises to solve your data storage and performance problems if you can afford them, However, there is more to buying an SSD than just the capacity - it's the grade or the class of the SSD. A consumer class 4TB SSD can be cheaper than an enterprise-class 2TB SSD so it's important to know the difference.
The low-cost consumer-grade SSDs ( like Samsung EVO, WD Green, Seagate Barracuda) are meant for consumer applications while the Expensive Enterprise Grade ( Like Samsung PM 883, WD Ultrastar, Seagate Nytro, and Kingston DC500) are used in DataCenters and corporate environments.
Let's see what makes an enterprise-class,enterprise-class.
Type of NAND
There are a number of cells in an SSD and each cell can contain data. If each cell can hold just one bit, it's an SLC. very fast, reliable but expensive. If the same cell stores 3 bits ( called a TLC), you have 3 times the capacity at the same price ( but it will be slower and more prone to errors). Samsung QVO has 4 bits per cell (QLC), so it's cheaper than even the TLC.
Generally, Enterprise SSDs will be SLC or MLC. Less number of bits stored per cell = more reliability = less capacity = more expensive.
Endurance and over-provisioning
Enterprise hard drives have higher endurance thanks to overprovisioning (OP). Imagine a 2.4TB drive sold as a 1.9TB drive, with 0.5TB overprovisioned). This 0.5TB of spare blocks are always available to the background process so the performance doesn't decline with time. OP also provides a higher endurance to the Enterprise SSD.
On the other hand, with consumer-grade SSDs, as the drive starts to fill up, the performance declines. All the great transfer numbers you see on the consumer-grade SSDs specification sheets are FOB ( fresh out of the box transfer rates), and they will decline as you start to fill your drive up. |
Enterprise drives will have steady, predictable transfer rates throughout the life of the product.
Specific Use case models- Write more, read more...
Enterprise SSDs can be had in specific models. For example, if you need an SSD for a Webserver or CDN where there are more reads than writes, you can have a read-centric SSD which will be priced lower than a write-centric or a mixed-use SSD. The same is the case with caching which doesn't change much, you can deploy a read-centric SSD.
With an enterprise application, you always would know what you want, and you can get a specific drive for that specific need. No such specific models exist for consumer class.
Today the highest capacity available on Enterprise SSD is 15.36TB, while on the consumer-grade it's just 4TB. What keeps the capacity low in the consumer class SSD is a lack of demand for high capacity and the overhead a higher capacity would put on the SSD controller.
Interface: SATA, Dual Port SAS, NVMe, U.2
While the consumer-grade SSDs are only available in SATA ( 2.5" or M.2) and NVMe, the enterprise SSDs come with Dual-port 12G SAS and U.2 Format as well. SAS has a dual port and higher transfer rates advantage for enterprise applications and U.2 is an extremely promising format with large capacities and Hot Plug capabilities. Both SAS and U.2 are only available in Enterprise
Since the hardware ( including the NAND chip and controller) on enterprise SSD is superior to consumer-grade, the Enterprise SSDs also ship with a higher warranty and with better vendor support. If you have an enterprise application, don't make the mistake of choosing a consumer-grade SSD for that application. Look at the class of the SSD and choose what your application needs.