Second in the Samsung and Dell Tech Center blog series:
Now that you have made the decision to adopt Solid State Drives (SSDs) in your data center, choices abound. As with any evolving data center technology, there are options to suit your unique compute environment — whether your primary concern is cost or performance.
You are certainly familiar with the standard storage interfaces: SATA, SAS and PCIe. However, you may not be familiar with the performance improvements that have occurred over the past few years, and how these recent technological improvements may play a critical role as you determine which SSDs to choose for your environment.
SATA remains the most prevalent interface choice in the data center, and has undergone a series of revisions that have increased its capabilities. The latest revision (SATA 3.x) supports throughput of 6Gbps, a 2x improvement over earlier versions (which are still prevalent in older systems). Because current SATA drives are backwards-compatible, they will still function in older systems but will not achieve the performance gains in newer systems supporting SATA 3.x.
Common in many external storage enclosures, the throughput of Serial Attached SCSI (SAS) drives have also increased over time, currently supporting 12Gbps. SAS is popular in enterprise applications because it is dual-ported, enabling redundancy. The SCSI command set used in SAS also provides additional commands suited for enterprise environments. The performance improvements of SAS (along with continued reductions in price) mean that many organizations are now deploying entry-level SSD storage arrays.
The most significant development with SSD interfaces is the introduction of PCIe. Until recently, the use of PCIe for SSDs was a niche application, requiring proprietary drivers. With the standardization of NVMe (Non-Volatile Memory express), the incredible speeds possible with a PCIe SSD interface have been brought to the mainstream market. The latest version of PCIe enables 8Gbps throughput per lane. An NVMe PCIe SSD is typically equipped to use four lanes, enabling an interface that supports up to 32Gbps. The NVMe protocol also provides more efficient access from the host to the drive, significantly reducing latency compared to SAS or SATA interfaces.
In addition to increased throughput, SSDs support greater capacity than ever (Samsung has a 3.8TB SSD at the time of this writing). However, there may be limitations to the size of drive you can use if your workload requires a minimum IOPs/GB. Denser SSD capacities may result in the IOPs/GB minimum not being met – unless the faster PCIe interface is used.
The chart below offers a comparison of the SATA, SAS, and NVMe PCIe SSDs based on a set of commonly used criteria:
• Sequential reads: A measure of how quickly large files can be read from a device in blocks of data that are adjacent to one another in the drive;
• Sequential writes: A measure of how quickly large files can be written to a device in blocks of data, also adjacent to one another;
• 4K random reads (IOPS): A measure of how quickly multiple small files can be read from a device where the files are 4 kilobyte blocks of data found at random locations on the device;
• 4K random writes (IOPS): A measure of how quickly small files can be written to a device in 4 kilobyte blocks of data to random locations on the device.
|SATA SSD||SAS SSD||NVMe PCIe SSD|
|Interface||6Gbps SATA||12Gbps SAS||32Gbps PCIe|
|Sequential reads (throughput)||~500MB/s||~1100MB/s||3000MB/s|
|Sequential writes (throughput)||~365MB/s||765MB/s||1350MB/s|
|4K random reads (IOPS)||~75,000||~130,000||750,000|
|4K random writes (IOPS)||~36,000||~100,000||110,000|
As noted, the PCIe interface supports the fastest throughput and, therefore, the highest performance numbers.
Samsung was the first to offer a PCIe SSD using the NVMe protocol, enabling customers to achieve historic performance levels. The Dell PowerEdge R920, the first to deploy the Samsung NVMe PCIe SSD (which can write random data in 25 microseconds), features markedly increased performance for big data tasks. This design is significantly faster than HDD-based systems in high performance computing applications. In fact, the performance of a single Samsung NVMe PCIe SSD can provide the random read performance of over 1800 of the fastest hard drives available in the market today. This results in power, cost, as well as space savings in your data center.
You’re now ready to make informed storage decisions. And you want to make them count. As current trends in the SSD arena suggest, you can clearly step on the accelerator by investing in an NMVe PCIe SSD.
For more information about Samsung SSDs, please visit: http://www.samsung.com/global/business/semiconductor/product/flash-ssd/overview
For more information about the Dell PowerEdge R920 featuring the Samsung NVMe SSD, please visit: http://www.dell.com/us/business/p/poweredge-r920/pd