More Speed for your SSD - NVME Expected to Replace SATA and SAS in the Future

Written By: Ontrack

Date Published: Sep 15, 2017 12:00:00 AM

More Speed for your SSD - NVME Expected to Replace SATA and SAS in the Future

While traditional hard drives appear to be sticking around for a while, chip-based solid state drives (SSDs) continue to advance and improve in sales and are becoming a large part of the future. Experts from Gartner are expecting that total revenues from SSDs will exceed those from hard disk drives (HDDs) for the first time in history this year. Although not all experts in the market agree to that forecast, they do agree that SSDs will continue with positive momentum in the market. Some journalists say that the battle between HDD and the SSD is therefore already over, with SSDs having won the fight.  The reason for SSD success is rather obvious – speed.

Initially, just laptops and simple desktop computers were were utilizing SSDs.  Now more and more manufacturers use them in high-end server and storage systems. This is due to the fact that prices have fallen dramatically in recent years.

However, only using NAND-FLASH SSDs, or other chips based on a more advanced successor and non-volatile storage technology, is simply not enough to boost a storage system or server. Performance and input/output (I/O) gains is obtainable by using more advanced interface protocols.

This is where NVMe comes into play. Prior to the SSD emerging in the market, finding, addressing and saving or copying every block of data successfully has been the concept of storing data on a traditional HDD.  This concept works fine with the read/write head built into a traditional HDD.

This is exactly how data is accessible through the read/write head. The data is found on the disk and by moving the head to the specific spot, the data is read out and transferred using a certain protocol specific to this task. With the (parallel) ATA interface and IDE bus, it was possible to transfer the data in 16-Bit-Packs. However, those 16 parallel data lanes of ATA posed challenges when transferring the data.  Asynchrony of these lanes and undesirable mutual interference between them. Therefore serial (S) ATA was invented.  With SATA, only one data lane is used for transferring the data bit-by-bit back and from the disk with one command. As CPUs and RAMs get faster and faster, the data transfer rates over these old Bus-Interfaces and standards is one of the main bottlenecks. With high demand of software which is able to almost instantly access, calculate or store big junks of data (Big Data), input/output (I/O) rates more important than ever right now.

Although the idea of such transmission protocols with SATA (based on the ATA command set) and SAS (based on SCSI) worked fine for more than 15 years, it is not useful anymore. The reason is simple: it is possible (and it makes more sense to use that possibility) that the logic behind an OS “can see” all content saved on a single chip or several chips on a SSD at once. Additionally, while it was only possible to do one command in a queue with SATA, the new NVMe protocol makes it possible for 65,000 commands in a queue to be handled simultaneously. Queue command depths of 254 (SAS) and 32 (SATA) compare to 65,000 queues (NVMe).

NVMe is a standard that is connected with the peripheral component interconnect express (PCIe) bus. The main benefit of this standard is that it achieves much greater bandwidth than SATA and SAS.  While SATA III provides 6Gbps and 600 Mbps throughput and SAS 12 Gbps and 8 Gbps throughput, NVMe offers a data transfer performance of circa 1 Gbps per lane, which is 16 Gbps in a 16 lane configuration. With this increase in I/O performance ability as well as throughput figures, it is obvious that storages with SSDs that are utilizing NVMe should be immune to severe overloads and performance degradation due to too many I/O requests.

That is the reason why, for example, PCIe SSD cards with the NVMe protocol are having success on the market now. Developed especially for the so-called ALL-FLASH storage systems, many of those are built into storage or server systems that can store or access data and information faster than ever before. However, the producers of SATA and SAS-based SSD storage cards are still fighting a hard battle with their new opponent and are far from giving up yet. Many SSDs are introduced in the market based on these old standard concepts. However, NVMe will most likely be the winner in the long run, It might be wise to upgrade your storage system on the new NVMe standard.

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