Over-buying or over-spec’ing an SSD solution is all too common because managers often aren’t completely sure of the requirements for a particular application but can’t risk having their SSD fail or even underperform. The available options have been consumer-class drives and enterprise-class drives. But in these situations, where the workloads involved (and the maybe the SSDs as well) are not completely understood, data center managers have traditionally taken the safe route and picked enterprise drives. Now there’s an option in the middle, the M500DC from Micron.
Personal storage drives are built for the consumer computer market, where cost is their overriding design criterion. Because most users don’t push the limits of SSD technology, factors like drive endurance, reliability and performance may be less robust than on enterprise SSDs. Plus,most personal SSD users require a very low duty cycle. Typical use cases are sequential and read-heavy, which doesn’t stress the drive like more write-intensive, random activity does. Personal SSDs typically support less than one drive fill per day, offer very few reliability features and have modest endurance – all in the name of the lowest price for a given capacity.
In addition, personal storage drives are also widely used in the “hyperscale” market, the cloud and large service providers that favor scale-out storage infrastructures comprised of commodity hardware. These sophisticated users know their environments very well and have designed highly resilient storage systems that support non-disruptive component replacement. More concerned about cost than about individual drive reliability or longevity, for them, consumer-grade SSDs are a good fit.
At the other end of the spectrum are traditional enterprise SSDs which are designed to offer the highest possible performance and the greatest possible endurance. Here, cost is a lesser concern. These products typically support up to 10 drive fills per day and offer the best performance and endurance flash can deliver. They have been the SSD solutions of choice for enterprise data centers with a need for superior performance and longevity but especially reliability. But as data center managers get more comfortable with SSD technologies and better able to characterize the workloads they’re running on these enterprise drives, it’s becoming clear to many that they have over-bought.
SSD Users Need More Choices
Many SSD users are getting more familiar with the concept of NAND flash’s finite life span and the importance of read and write percentages, since only writes impact drive endurance. Many recognize the fact that specs like “drive fills per day” can be misleading, since most applications probably don’t generate the write activity to fill a flash drive every day. For them, Total Bytes Written (TBW) is a more accurate product spec.
Many users are also gaining a better understanding of their own requirements, in terms of read/write mix and I/O or throughput, so they’re better able to determine how much performance they really need. They still need enterprise-grade reliability and predictable performance, but not 10 drive fills per day, as an example.
For many of these SSD users, the question is how to “walk back down” that cost curve after buying higher-priced enterprise drives. The first thing that’s needed is a lower cost alternative that still offers predictable performance and high reliability.
Designed for 24/7 data center workloads Micron’s M500DC is a 20nm, MLC SATA SSD that’s available in 1.8” and 2.5” form factors with capacities of 120GB, 240GB, 480GB and 800GB. This enterprise-grade solid state drive is able to provide ~2 drive fills per day for 5 years, based on random input recorded. In terms of TBW that’s up to 1.9PB.
All drive capacities provide steady-state random read performance of 425 MB/s and 63,000 IOPS (800GB drives slightly higher) with 0.5ms latency. Random write performance is 375 MB/s and 35,000 IOPS steady-state, depending on drive capacity, with 1.5ms latency. The M500DC offers a lower TCO as well, with reduced power consumption and an MTTF (Mean Time To Failure) of 2.0M hours. It also features enterprise-class technology to improve reliability and data protection.
XPERT is the acronym for eXtended Performance and Enhanced Reliability Technology, Micron’s NAND flash storage architecture enhancements. These features, developed for Micron’s enterprise class of SSDs, include processes for protecting data that’s safely stored on the NAND flash and data that’s “in flight” within the SSD itself.
DataSAFE protects the data while it’s in the data path by recording the critical metadata with each transfer and through the use of Memory Protection Error Correction Code (MPECC) which ensures accuracy as data passes through the SSD’s DRAM. An additional level of “at rest” data protection is afforded by RAIN (Redundant Array of Independent NAND). This parity-based process, which goes well beyond common error correction code (ECC), can rebuild data blocks after media failures or corruption.
Adaptive Read Management/Optimized Read (ARM/OR) is a process that samples the stored data and dynamically tunes the NAND device in the background. This helps compensate for the changes that occur to the substrate over time, improving its effectiveness in accurately reproducing data and increasing overall performance. If a read error does occur, ARM/OR will execute foreground mode operations, actively compensating for any dynamic changes in the NAND.
As an integrated supplier of solid state storage, Micron actually designs, manufactures, and qualifies the flash chips that go into their SSDs. This gives them a special understanding of the behavior of NAND flash that produces some unique design insights. It also means Micron has an assured source of supply, something most other SSD vendors can’t claim. In addition, Micron has the infrastructure and resources in place to deliver the enterprise-grade support that enterprises are accustomed to.
Storage Swiss Take
SSD users are getting more sophisticated. They’re recognizing that the enterprise drives they’ve been buying are often more than they really need. In order to get drives that are reliable enough, they’ve been over-buying SSD performance and drive endurance. Now, as users become more familiar with the nuances of NAND flash wear and how their individual applications use that flash capacity, they’re realizing they need another alternative between consumer SSDs and the higher-end enterprise SSDs.
Micron has a drive that’s designed for this middle ground – good enough for the enterprise but still able to provide some real cost savings for users who know what they really need. They’ve taken some of their technology developed for the enterprise and incorporated it into the M500DC, an SSD that balances performance, endurance and cost, while maintaining reliability.
Micron is a client of Storage Switzerland