{"id":6242,"date":"2021-01-22T16:00:25","date_gmt":"2021-01-22T14:00:25","guid":{"rendered":"https:\/\/tekmart.co.za\/t-blog\/?p=6242"},"modified":"2021-01-22T16:00:27","modified_gmt":"2021-01-22T14:00:27","slug":"sas-vs-nvme-the-future-of-the-two-key-storage-interfaces","status":"publish","type":"post","link":"https:\/\/tekmart.co.za\/t-blog\/sas-vs-nvme-the-future-of-the-two-key-storage-interfaces\/","title":{"rendered":"SAS vs. NVMe: The future of the two key storage interfaces"},"content":{"rendered":"Reading Time-approximately:<\/span> 6<\/span> minutes<\/span><\/span>\n

SAS and NVMe both play significant roles in enterprise storage. See how the two interfaces stack up in terms of performance, scalability, flexibility, manageability and the future.<\/strong><\/h2>\n\n\n\n
\"Stacey<\/figure>\n\n\n\n

By Stacey Peterson<\/a><\/p>\n\n\n\n

As\u00a0NVMe\u00a0SSDs make inroads into the enterprise market, the question remains: <\/p>\n\n\n\n

What’s in store for SAS drives? While they don’t provide the performance enhancements and latency reduction of NVMe SSDs, they do have a future.<\/p><\/blockquote><\/figure>\n\n\n\n

For all enterprise storage — HDDs and SSDs combined — SAS drives dominate in terms of exabytes (EB) shipped, and they will continue to dominate the market for years to come, according to the analyst firm TrendFocus Inc. Nevertheless, TrendFocus found PCIe-based drives surpassed SAS and SATA SSDs in 2019 by nearly 2 EB shipped. <\/p>\n\n\n\n

That’s a trend expected to continue in the SAS vs. NVMe rivalry, as\u00a0NVMe brings speed and efficiency advantages\u00a0to the SSD market. NVMe uses PCIe to transfer data to SSDs.<\/p>\n\n\n\n

“The pendulum has swung; there’s no looking back,” said Don Jeanette, a vice president at TrendFocus. “NVMe is now the dominant interface for all enterprise SSDs.” Nevertheless,\u00a0SAS and SATA drives\u00a0still account for more than a third of SSD exabytes shipped, he said.<\/p>\n\n\n\n

To compare SAS- vs. NVMe-based SSDs, the SCSI Trade Association brought together two industry executives: SCSI Trade Association President Cameron Brett, who is also director of enterprise and cloud storage marketing at memory and SSD manufacturer Kioxia, and Jonmichael Hands, co-chair of the NVM Express Inc. marketing work group and senior strategic planner and product manager at Intel. They looked at the performance and scalability, flexibility, and manageability and serviceability capabilities of both technologies.<\/p>\n\n\n\n

SAS assessment<\/strong><\/h3>\n\n\n\n

SAS\u00a0is part of the ongoing SCSI development effort led by the T10 Technical Committee of the InterNational Committee on Information Technology Standards and backed by more than 50 companies.<\/p>\n\n\n\n

Performance and scalability<\/strong><\/h4>\n\n\n\n

When you look at the spec sheets, SAS drives inevitably come up short in the\u00a0SAS vs. NVMe PCIe SSD comparison. However, there’s more to it than the spec sheet numbers, according to Brett. For instance, in a lane-by-lane comparison, a 24G SAS link with 2.4 GBps throughput outperforms a single PCIe 4.0 lane at 2 GBps, Brett said.<\/p>\n\n\n\n

The pendulum has swung; there’s no looking back. NVMe is now the dominant interface for all enterprise SSDs.<\/p>

Don Jeanette<\/strong>, Vice president, TrendFocus<\/p><\/blockquote>\n\n\n\n

NVMe PCIe SSDs typically use four lanes to connect to a host, which means they end up using more host resources, such as memory and power, than SAS drives, which typically use one or two links, Brett said. In addition, most applications don’t need the million IOPS provided per NVMe drive, he added, but those drives use more host resources to service that level of performance.<\/p>\n\n\n\n

SAS also comes up short in the\u00a0SAS vs. NVMe comparison\u00a0in terms of scalability. But here, too, there are extenuating circumstances, Brett said. “SAS may not scale at the same rate as NVMe, but [it] scales in a different way,” he said.<\/p>\n\n\n\n

SAS is designed to accommodate configurations of 64,000 end devices. Given the amount of memory needed, that many devices aren’t usually supported, Brett said. However, setups of around 2,000 devices can be found in real-world configurations.<\/p>\n\n\n\n

In addition, it’s common to run SAS-based arrays connected to a SAN that’s built on SCSI technology. SANs typically have multiple hosts, Brett noted, and you can\u00a0dynamically scale SAS storage\u00a0by adding disks or arrays without shutting down the system. SAS enables cross-rack, -room and -data center connectivity options, he added.<\/p>\n\n\n\n

Flexibility<\/strong><\/h4>\n\n\n\n

SAS, with its\u00a02.5- and 3.5-inch drive form factors, has fewer form factor options than NVMe SSDs. But, Brett noted, there are other ways SAS demonstrates flexibility. SAS connects to more device types than NVMe, and it has more flexibility at the architectural level, he said.<\/p>\n\n\n\n

SAS connections and backplanes natively support SAS and SATA protocols, hard drives and SSDs, as well as optical and tape drives. “That’s a few more device types on a SAS connection than NVMe does today,” he said.<\/p>\n\n\n\n

SAS also lets you create fully tiered environments with a caching layer; a warm tier that houses large amounts of regularly accessed data; and an archival cold tier that uses low-cost, high-capacity hard drives, Brett added.<\/p>\n\n\n\n

SAS manageability and serviceability<\/strong><\/h4>\n\n\n\n

The SCSI Enclosure Services (SES) protocol was created as\u00a0part of the SAS-3 spec, providing in-band and out-of-band ways to communicate with a SCSI array and the devices inside an array. The enclosure houses SCSI devices and non-SCSI supporting devices, such as power supplies, fans, displays and sensors, Brett said. A controller manages the connection, and management tools are available that work with and support the SES.<\/p>\n\n\n\n

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