Micron Announces Broad Availability Of 5210 ION QLC SSDby Billy Tallis on November 8, 2018 8:00 AM EST
Micron's 5210 ION enterprise SATA SSD was announced in May as the first shipping SSD with four bit per cell (QLC) NAND flash memory, but until now it has only been available to Micron's largest customers and partners. Starting this week, the 5210 ION is getting a broad release that will include sales through online retailers. This means that we finally have concrete detailed specifications and prices for the 5210.
As originally announced, the 5210 ION is a fairly straightforward adaptation of the 5200 series TLC-based enterprise SATA SSDs to use Micron's new QLC NAND. The controller and most of the firmware are the same, and the change in flash memory brings lower cost, write endurance and performance. We now have a clear idea of just how big an impact the switch to QLC NAND makes on those specifications.
|Micron 5210 ION Series Specifications|
|Capacity||1.92 TB||3.84 TB||7.68 TB|
|Form Factor||2.5" SATA 6 Gbps|
|NAND||Micron 64-layer 3D TLC NAND|
|Sequential Read||540 MB/s|
|Sequential Write||260 MB/s||350 MB/s||360 MB/s|
|4KB Random Read||70k IOPS||83k IOPS||90k IOPS|
|4KB Random Write||13k IOPS||6.5k IOPS||4.5k IOPS|
|Idle Power||1.5 W|
|Max Read Power||2.8 W|
|Max Write Power||3.6 W|
Micron's primary goal with the 5210 ION is to expand the market for their enterprise SSDs. Micron does expect some customers to replace some of their TLC-based enterprise SSDs with QLC drives like the 5210 ION, but they're more interested in going after the remaining market for 10k RPM hard drives. Micron believes that with the 5210 they finally have a SSD that is cost-competitive with high-end hard drives, while offering higher performance, density, and power efficiency. Write speeds are the biggest weakness of QLC NAND, but even the smallest, slowest 5210 model can sustain sequential writes at least as fast as a 10k RPM hard drive.
However, the 5210 has already proven to have broader appeal, and Micron has some large customers that are deploying it as replacements for 7200RPM hard drives or client TLC SSDs that were being used in datacenters. With a price similar to consumer TLC drives but firmware tuned for enterprise workloads, the 2TB 5210 is being rolled out to replace 1TB consumer SSDs in service with a major streaming media CDN. Serving up streaming video is an appropriately read-heavy, mostly sequential workload that allows the 5210 to saturate the SATA link as well as any drive, but with more consistent latency than client/consumer SSDs offer.
Micron also cites a system builder of servers for machine learning is migrating from 8+TB 7200 RPM to the 8TB Micron 5210 ION for storing the massive datasets involved. The 5210 is quite a bit more expensive than the hard drives, but the hard drives have been a serious bottleneck. The higher performance of the 5210 allows these systems to perform tasks like image classification 8x faster, greatly improving the utilization of the expensive compute hardware in those machines and lowering the total cost of ownership. Machine learning can be an extremely read-heavy workload for inference tasks when a large model is consulted repeatedly and only occasionally updated.
Write Endurance Gets Complicated
With the 5210 ION, Micron has adopted a workload-dependent write endurance rating system. The same drive can be rated for anywhere from 0.05 drive writes per day up to 0.8 drive writes per day depending on how much of the data written is sequential vs random, and whether it is small 4kB random writes or larger block sizes. By contrast, their Crucial P1 consumer QLC SSD still gets a single number rating of 0.1 DWPD. By giving a wide range of endurance ratings, Micron avoids having to label the 5210 with a single conservative rating that would make it look particularly fragile compared to TLC-based SSDs. It also encourages their customers to be more aware of the details of their workload when shopping for storage. A gradual increase in that kind of awareness has been an important enabler for the transition from MLC to TLC, and is the main reason for the decline of enterprise SSDs with 10+ DWPD endurance ratings. (Micron claims that last year, 75% of all enterprise SSDs sold were rated for 1 DWPD or less, and that percentage will continue to grow.)
|Micron 5210 ION Series Write Endurance|
|Capacity||1.92 TB||3.84 TB||7.68 TB|
|100% 128kB Sequential||0.8 DWPD
|90% 128kB Sequential
10% 4kB Random
|80% 128kB Sequential
20% 4kB Random
|70% 128kB Sequential
30% 4kB Random
|50% 128kB Sequential
50% 4kB Random
|100% 16kB Random||0.20 DWPD
|100% 8kB Random||0.20 DWPD
|100% 4kB Random||0.20 DWPD
The patterns in the write endurance ratings are not completely uniform across the product line. All three capacities top out at 0.8 DWPD for 100% sequential 128kB writes, and are rated for 0.2 DWPD for 16kB random writes. When random writes of 4kB or 8kB are involved, the larger models have lower DWPD ratings than the 2TB model, possibly reflecting differences in how the flash translation layer is tuned for different drive capacities. The worst case is for 100% 4kB random writes, where the 2TB model is still rated for 0.2 DWPD but the 8TB model is rated for just 0.05 DWPD—the larger drive can't actually handle more total TB of 4k random writes.
Micron is pitching the 5210 as best suited for workloads that are at least 70% sequential for their writes, which yields endurance ratings of at least 0.27–0.56 DWPD depending on drive capacity. There are plenty of datacenter workloads that fall within this range, and in particular, workloads that hard drives (10k or 7200 RPM) offer sufficient performance for are probably already heavily sequential.
While Micron has announced general availability this week, distributors like CDW are not expecting stock for another week or two but are listing their prices for pre-orders. CDW currently lists the 5210 ION for 21-24 cents per GB, compared to 25-28 cents per GB for the TLC-based 5200 ECO. Bulk pricing should be significantly lower, and retail pricing may also drop below 20 cents per GB when supplies improve.
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PeachNCream - Thursday, November 8, 2018 - linkBack of the napkin calculations put individual memory cell P/E cycles at about 350-600. Meh.
WithoutWeakness - Thursday, November 8, 2018 - linkThere are still a lot of write-once-read-many workloads that can take advantage of the speed benefits that QLC SSDs bring over traditional hard drives without worrying about write endurance of the NAND. Despite the back-of-the-napkin low P/E rating calculations Micron still warranties all capacities for 5 years. They're clearly confident that the endurance will not be an issue as long as these are used for the intended use case. It's also important to remember that "unused" free space is still used for wear leveling so large drives like these will have even more free NAND available to help prevent individual cells from degrading.
FunBunny2 - Thursday, November 8, 2018 - link"They're clearly confident that the endurance will not be an issue as long as these are used for the intended use case."
and when one croaks, what evidence will Micron demand that drive was used per "intended use case"? sounds like a Catch-22 situation.
Billy Tallis - Thursday, November 8, 2018 - linkThe drive's SMART indicators give you plenty of fair warning if your workload is causing high write amplification leading to early wearout.
FunBunny2 - Thursday, November 8, 2018 - linkbut... does the SMART data survive the croak? real question, I've no idea.
Billy Tallis - Thursday, November 8, 2018 - linkIt should, barring a serious firmware bug. SSDs should go read-only when they exhaust their write endurance, so that the data can be recovered. Enterprise SSDs are expected to retain the data for at least three months after reaching this point, and the standard for consumer SSDs is a full year of retention at end of life. Some drives have been observed turning into an effective brick if you power cycle them after they go read-only, but even then the manufacturer has the ability to query the drive for surviving data, which includes the SMART indicators.
PeachNCream - Thursday, November 8, 2018 - linkThe 5 year warranty is indeed a good thing so there is that going for it.
tygrus - Friday, November 9, 2018 - linkCells have 1500 P/E cycles but write amplification can reduce the usable number of drive writes down to 92 (7.68TB model: worst case 4KB random write causes 64KB to be erased and re-written = 16x write amplification = 0.8/0.05). The larger the model, the larger the smallest write block can actually be to the underlying arrays.
Smaller drives have smaller blocks for these writes so random writes have smaller penalties (1.92TB model: worst case 4KB random write causes 16KB to be erased and re-written = 4x write amplification = 0.8/0.2).
stanleyipkiss - Thursday, November 8, 2018 - linkSell me a 8TB SATA SSD at less than $400 and I'll buy it. DWPD be damned.
bubblyboo - Thursday, November 8, 2018 - linkThose write IOPS are downright frightening