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TLC SSDs Make All-Flash Array Debut On Dell SC Series

By - Source: Dell

TLC in the datacenter is as inevitable as the transition from SLC to MLC was, and numerous All-Flash Array (AFA) vendors have expressed their intention of bringing the economical storage media to market. However, most are still working on software that can mitigate the endurance challenges associated with TLC NAND.

Dell has been on a mission to lower the entry level cost of AFAs through its Dell Storage SC4020 Series, which made waves when it debuted for a mere $25,000 in January. Now, Dell has taken the price of its arrays down another notch by being the first AFA vendor to market with 3D TLC SSDs.

One of the main attractions of TLC SSDs is their low price point. The Dell DC4020 AFA starts at $1.66-per-GB, and the hybrid configuration starts at $0.58-per-GB. Dell's price quoting stands in stark contrast to the other AFA vendors because it calculates the price before applying data reduction technologies. The majority of AFA vendors quote price with deduplication and compression factored into the equation, but these calculations muddy the waters because every workload and environment will experience varying levels of success with data reduction techniques. Dell is touting the fact that even before dedupe and compression, its cost is lower than the competition, even when the other vendors factor these techniques into the overall cost.

Factoring in data reduction additives will lower Dell's prices even further, and TLC SSDs are now actually the same price as a 15K HDD but come with a 24x performance improvement and lower power consumption.

TLC SSDs offer stellar read performance, but a tradeoff in overall endurance enables them to provide increased density and a much lower price point. The new Dell SSDs offer an incredible 3.8 TB of storage in a standard SATA 2.5" form factor SSD, which is more than the 1.9 TB Dell currently offers with standard MLC SSDs. Dell's new Mainstream RI (Read-Intensive) TLC SSDs enable up to 90 TB of flash capacity in a 2U rack space. As a result, the Dell SC8000 now offers up to 63 percent more flash and up to 3 PB of raw flash per array.

TLC SSDs have lower write endurance than SLC or MLC SSDs, but Dell already laid the groundwork for TLC SSDs in its 6.4 software by optimizing its arrays for flash tiering. Dell has a virtualized storage architecture, and its updated Data Progression technology (6.6 software) intelligently identifies data traffic and routes it into a two-tier storage pool. The write-intensive tier consists of either SLC or MLC SSDs, and the read-intensive tier employs either MLC or TLC SSDs. The write-intensive tier absorbs the punishing write workloads on more endurant media and then passes that data down to the read-intensive tier as sequential data (which reduces SSD wear). Dell also provides a full warranty on the SSDs for the length of the service contract. 

Samsung is the only SSD vendor on the market with 3D NAND of any variety, and its as-of-yet unreleased 12 Gbps SAS PM1633 is the only 3D TLC SSD that fits the description of Dell's latest offering. We spotted the 32-layer TLC V-NAND PM1633 at CES earlier this year. It offers sequential read/write speeds of 1,100/1,000 MBps, and 4K random read/write speeds of 180,000/15,000 IOPS. The SSDs come with all of the enterprise trimmings, such as full power fail support, and they utilize Samsung's proprietary REX controller.

Dell's low entry-level cost has already fueled an 89 percent year-over-year growth for the SC Series AFA and hybrids, and the new TLC SSDs allow Dell to provide the industry's lowest cost-per-GB of flash storage in an AFA. Some users might be reluctant to leverage TLC SSDs, but the steps Dell has taken to mitigate the lower endurance threshold are rooted in solid design principles, and the warranty should assuage some of the more cautious administrators.

The new SSDs will be available in August 2015 for the Dell Storage SC8000, SC4020 and SCv2000 Series.

Paul Alcorn is a Contributing Editor for Tom's IT Pro, covering Storage. Follow him on Twitter and Google+.

EDIT: 7/20/2015 11:00 AM - Corrected typo in title.

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