Taking an Accurate Look at SSD Write Endurance
Last year, I posted a rebuttal to a paper describing the future of flash memory as ‘bleak’. The paper went through great (and convoluted) lengths to paint a tragic picture of flash memory endurance moving forward. Yesterday a newer paper hit Slashdot – this one doing just the opposite, and going as far as to assume production flash memory handling up to 1 Million erase cycles. You’d think that since I’m constantly pushing flash memory as a viable, reliable, and super-fast successor to Hard Disks (aka 'Spinning Rust'), that I’d just sit back on this one and let it fly. After all, it helps make my argument! Well, I can’t, because if there are errors published on a topic so important to me, it’s in the interest of journalistic integrity that I must now post an equal and opposite rebuttal to this one – even if it works against my case.
First I’m going to invite you to read through the paper in question. After doing so, I’m now going to pick it apart. Unfortunately I’m crunched for time today, so I’m going to reduce my dissertation into the form of some simple bulleted points:
- Max data write speed did not take into account 8/10 encoding, meaning 6Gb/sec = 600MB/sec, not 750MB/sec.
- The flash *page* size (8KB) and block sizes (2MB) chosen more closely resemble that of MLC parts (not SLC – see below for why this is important).
- The paper makes no reference to Write Amplification.
Perhaps the most glaring and significant is that all of the formulas, while correct, fail to consider the most important factor when dealing with flash memory writes – Write Amplification.
Before geting into it, I'll reference the excellent graphic that Anand put in his SSD Relapse piece:
SSD controllers combine smaller writes into larger ones in an attempt to speed up the effective write speed. This falls flat once all flash blocks have been written to at least once. From that point forward, the SSD must play musical chairs with the data on each and every small write. In a bad case, a single 4KB write turns into a 2MB write. For that example, Write Amplification would be a factor of 500, meaning the flash memory is cycled at 500x the rate calculated in the paper. Sure that’s an extreme example, but the point is that without referencing amplification at all, it is assumed to be a factor of 1, which would only be the case if you were only writing 2MB blocks of data to the SSD. This is almost never the case, regardless of Operating System.
After posters on Slashdot called out the author on his assumptions of rated P/E cycles, he went back and added two links to justify his figures. The problem is that the first links to a 2005 data sheet for 90nm SLC flash. Samsung’s 90nm flash was 1Gb per die (128MB). The packages were available with up to 4 dies each, and scaling up to a typical 16-chip SSD, that only gives you an 8GB SSD. Not very practical. That’s not to say 100k is an inaccurate figure for SLC endurance. It’s just a really bad reference to use is all. Here's a better one from the Flash Memory Summit a couple of years back:
The second link was a 2008 PR blast from Micron, based on their proposed pushing of the 34nm process to its limits. “One Million Write Cycles” was nothing more than a tag line for an achievement accomplished in a lab under ideal conditions. That figure was never reached in anything you could actually buy in a SATA SSD. A better reference would be from that same presentation at the Summit:
This shows larger process nodes hitting even beyond 1 million cycles (given sufficient additional error bits used for error correction), but remember it has to be something that is available and in a usable capacity to be practical for real world use, and that’s just not the case for the flash in the above chart.
At the end of the day, manufacturers must balance cost, capacity, and longevity. This forces a push towards smaller processes (for more capacity per cost), with the limit being how much endurance they are willing to give up in the process. In the end they choose based on what the customer needs. Enterprise use leans towards SLC or eMLC, as they are willing to spend more for the gain in endurance. Typical PC users get standard MLC and now even TLC, which are *good enough* for that application. It's worth noting that most SSD failures are not due to burning out all of the available flash P/E cycles. The vast majority are due to infant mortality failures of the controller or even due to buggy firmware. I've never written enough to any single consumer SSD (in normal operation) to wear out all of the flash. The closest I've come to a flash-related failure was when I had an ioDrive fail during testing by excessive heat causing a solder pad to lift on one of the flash chips.
All of this said, I’d love to see a revisit to the author’s well-structured paper – only based on the corrected assumptions I’ve outlined above. *That* is the type of paper I would reference when attempting to make *accurate* arguments for SSD endurance.
SAN JOSE, CA—February 19, 2012—OCZ Technology Group, Inc. (Nasdaq:OCZ), a leading provider of high-performance solid-state drives (SSDs) for computing devices and systems, today announced a new 20 nanometer (nm) NAND flash version of its award-winning Vertex 3 SSD Series. The new Vertex 3.20 SSD is a 2.5-inch, 6Gbps SATA III-based Multi-Level Cell (MLC) drive that implements the feature-set of the Vertex 3 Series but is built around smaller, state-of-the-art NAND flash process geometry.
Being that the Vertex 3 Series is one of OCZ’s most popular SSDs to date, and has received numerous accolades from media reviewers globally, the implementation of 20nm NAND flash will extend its availability and enable mainstream users of mobile and desktop platforms to improve gaming, multimedia, and the overall computing experience over traditional hard disk drives (HDDs) and other competing SSDs. The Vertex 3.20 SSD will be available in 120GB and 240GB storage capacities, with 480GB capacities to follow soon.
Utilizing the proven and effective LSI SandForce® SF-2200 processor, the Vertex 3.20 SSD delivers exceptional performance of synchronous 20nm NAND flash supporting read bandwidth up to 550MB/s, write bandwidth up to 520MB/s, random read performance up to 35,000 input/output operations per second (IOPS), and random write performance up to 65,000 IOPS. It is also optimized to provide excellent endurance and reliability coupled with power efficiency.
“OCZ is always looking for ways to deliver superior solid state drive storage performance and features, as well as making this technology more accessible to the complete range of customers,” said Daryl Lang, Senior Vice President of Product Management for OCZ Technology. “The Vertex 3 has been a popular SSD series among consumers and implementing the newer, smaller process geometry will not only extend its life, but enables mainstream users with an excellent computing experience at a competitive price point.”
The Vertex 3.20 SSD is supported by a 3-year warranty to ensure customer satisfaction and will be available shortly through OCZ’s global channel in 120GB and 240GB storage capacities.
Subject: Storage | February 15, 2013 - 09:26 PM | Jeremy Hellstrom
Tagged: vector, ssd, sata, ocz, mlc, Indilinx Barefoot
Just in case you forgot how impressive the OCZ Vector 256GB is, Overclockers Club would like to remind you. The Indilinx Barefoot 3 controller is matched with low cost 25nm MLC IMFT NAND modules and 512MB of DDR3-1600 RAM for a cache. That translates to incredibly fast performance but without the high price of other drives. The 256GB model sits currently just under $1/GB, it is not the least expensive SSD available but when you consider the speeds this drive operates at it is the best value. Remind yourself where OCZ's Vector sits in the pack by reading on at OCC.
"OCZ's Vector line of solid state drives is every bit the performer that the Vertex 4 drives are with very few exceptions. In many of the tests, the two fastest drives were the Vertex 4 and OCZ's latest Indilinx Barefoot 3-equipped Vector. The only real weakness I saw was that the Vector was less frugal with the CPU cycles than the other Indilinx equipped drives. OCZ's move to the Barefoot 3 controller is beginning to pay dividends as it uses the technologies it has available in-house after the Indilinx and PLX acquisitions. It's taken a while to go all-in but that time has come. As the first totally in-house designed controller from OCZ, it seems to have hit on a controller that does better at managing real world usage scenarios and handling both compressible and incompressible data streams.”
Here are some more Storage reviews from around the web:
- OCZ Vector 256GB Solid State Drive Review @ OCIA
- Micron P400m 200GB Enterprise SSD @ Tweaktown
- Samsung 840 Pro 256GB SSD @ Tweaktown
- Samsung 840 SSD Storage Endurance Testing - TLC to the End @ Tweaktown
- kingston HyperX 3K 120GB SSD Review @ XtremeComputing
- Intel DC S3700 800GB Enterprise SSD @ Tweaktown
- Intel 525 Series mSATA SSD Performance Roundup @ Legit Reviews
- Plextor M5M 128GB review: the mSATA version of the M5 Pro @ Hardware.info
- Plextor 128GB M5M mSATA @ Kitguru
- MyDigitalSSD BP4 120GB SSD Review - SATA 3 At an Amazing Price @ SSD Review
- Micron P400m @ AnandTech
- Intel 525 mSATA SSD Review – Every Capacity Tested @ HCW
- Intel SSD 335 vs. Intel SSD 330 Review: Inexpensive SSD Evolution @ X-bit Labs
- Western Digital Red Hard Disk Drives for Network Attached Storage @ X-bit Labs
- Seagate Enterprise Capacity 3.5 V.3 4TB SATA III HDD Review @ NikKTech
- HighPoint RocketStor 5322 Review @ OCC
- Kingston Wi-Drive MobileLite Wireless Card Reader Preview @ Legit Reviews
- Kingston DataTraveler HyperX Predator 512GB Flash Drive Review @ Techgage
- Kingston DataTraveler Ultimate G3 64GB USB 3.0 Flash Drive Review @ NikKTech
- SanDisk Extreme 64GB USB 3.0 Flash Drive @ Tweaktown
- Thecus N5550 @ Legion Hardware
- Thecus Top Tower N8850 review: a powerful eight-disk NAS device @ Hardware.info
- 24 two-bay NAS device group test @ Hardware.info
- Transcend StoreJet 25M3 1 TB External USB 3.0 HDD Review @ OCC
Subject: Storage | February 5, 2013 - 08:16 AM | Tim Verry
Tagged: ssd, SandForce SF-2281, sandforce, mlc, intel 335, Intel
Intel has added a new drive to its existing 335 SSD series. The new drive offers up 180GB of storage, but maintains the same level of read and write performance as its larger 240GB sibling.
The 180GB version uses 20nm MLC NAND flash paired with a SandForce SF-2281 controller. According to the Intel-provided spec sheet (PDF), the new drive is capable of sustained read and write speeds of 500 MB/s and 450 MB/s respectively. Further, the drive maxes out at 42,000 random read IOPS and 52,000 random write IOPS.
The drive will come in the 2.5” form factor, but is 9.5mm thick (meaning it will not work in all notebooks). Reportedly, Intel has redesigned the casing to include a schematic/blueprint graphic alongside the Intel logo.
Intel rates the 180GB 335 series SSD at 1.2 million MTBF and is warranted for three years. The drive can currently be found online for around $180, making it right around the $1/GB mark. Interestingly, the larger 240GB model is currently retailing for around $195. Therefore, if you can spare the extra $15, the 240GB model is the better deal.
Subject: Storage | February 4, 2013 - 07:09 PM | Jeremy Hellstrom
Tagged: kingston, ssdnow v300, SF-2281 controller, mlc
Kingston's updated SSDNow V300 uses 19nm Toshiba Toggle NAND and the SandForce 2281 controller with some unspecified enhancements. Kingston has made a name for themselves in the SSD market for offering an easy and fully explained upgrade path for users who are unfamiliar with changing hard drives. The updated version is no different, included is an external enclosure for the SSD and a USB cable to allow users to easily copy over any data which is of great benefit for users who don't have several enclosures laying around. [H]ard|OCP's testing showed that even though this is a value priced drive, it also performs better than a lot of the competition.
"The Kingston SSDNow V300 is yet another value-oriented SSD in Kingston's wildly successful line of mainstream solid state drives. With the pressures of TLC SSDs squeezing the value market we take a look and see if a standard MLC SSD with 19nm Toshiba Toggle NAND and an SF-2281 processor can keep up with the changing times."
Here are some more Storage reviews from around the web:
- Kngston SSD Now 300V 120GB Review @ OCC
- OCZ Vector 256GB @ Bjorn3D
- The Full Intel SSD 525 Review: 30GB, 60GB, 120GB, 180GB & 240GB Tested @ AnandTech
- Intel SSD 525 @ AnandTech
- Plextor M5 Pro Extreme SSD @ SSD Review
- Icy Dock FlexCage MB973SP-B and MB974SP-B SATA Review Update @ Hi Tech Legion
- SanDisk Ultra Plus 256GB @ Tweaktown
- Toshiba THNSNF256GCSS 'Thin Sniff' 256GB @ Tweaktown
- Intel DC S3700 SSD Review; Home User Edition @ Hardware Canucks
- OCZ Vector 256GB @ Funkykit
- Transcend SSD320 & SSD720 (256GB) @ AnandTech
- MyDigitalSSD SMART & BP3 mSATA SSD @ AnandTech
- Taking a look at MEGA (beta) - cloud storage, done safely? @ Tweaktown
- G-Technology G-DRIVE 4TB Professional High Performance External HDD Review @ NikKTech
- 4-Bay NAS from Synology: Three Models Reviewed @ X-bit Labs
- QNAP TS-669 Pro @ CoD
- RaidSonic ICY BOX IB-RD2121StS 2x2.5" to 3.5" HDD/SSD RAID Converter Review @ NikKTech
- ADATA DashDrive Elite HE720 External Drive @ Benchmark Reviews
- Kingston DataTraveler Hyper X Predator 512GB USB 3.0 Flash Drive @ SSD Review
- Silicon Power Marvel M60 32GB USB 3.0 Flash Drive Review @ ModSynergy
- Kingston DataTraveler Ultimate 3.0 G3 64GB USB Thumb Drive @ TechwareLabs
- Kingston DataTraveler HyperX PREDATOR 512GB USB 3.0 Flash Drive Review @ NikKTech
Subject: Storage | November 27, 2012 - 09:47 PM | Jeremy Hellstrom
Tagged: vector, ssd, sata, ocz, mlc, barefoot 3
There are three members of the OCZ Vector SSD, the 128GB and 256GB models will have 512MB cache and the 512GB model 1GB of cache, each costing a bit over $1/GB. Inside is the brand new Barefoot 3 controller which features 8 channels and both an ARM cortex processor and OCZ's secret sauce, the Aragon co-processor. On paper, the 256GB and 512GB models have the same performance specs with the 128GB model having slightly slower sequential writes and 4k reads, though still the speeds are impressive enough that you won't suffer unduly. [H]ard|OCP takes you through their torture test here and of course if you haven't seen what Allyn did to them, get reading!
"OCZ soft launches the 256GB Vector SSD with its first OCZ-proprietary controller, the Barefoot 3. Geared for steady state performance, the OCZ Vector SSD is designed with the end user in mind. Today we take a look at the Vector and the new controller architecture and see how these fare in our steady state testing."
Here are some more Storage reviews from around the web:
- OCZ's Vector SSD @ The Tech Report
- OCZ Vector SSD Review - Indilinx Barefoot 3 Becomes Reality @ SSD Review
- OCZ Vector 256GB @ TechSpot
- OCZ Vector 256GB @ Kitguru
- OCZ Vector SSD Launch @ Hardwareheaven
- OCZ Vector 256GB @ Tweaktown
- OCZ Vector 256GB SSD @ Hardware.info
- OCZ Vector SSD @ Guru of 3D
- OCZ Vector 256GB SSD Review @ Hardware Canucks
- OCZ Vector 256GB Indilinx Barefoot 3 SSD Review @ Legit Reviews
- Kingston HyperX 3K 240GB SSD @ DVHardware
Subject: Storage | November 27, 2012 - 08:48 PM | Jeremy Hellstrom
Tagged: vector, ssd, sata, ocz, mlc, barefoot 3
SAN JOSE, CA – November 27, 2012 - OCZ Technology Group, Inc. (Nasdaq:OCZ), a leading provider of high-performance solid-state drives (SSDs) for computing devices and systems, today announced the availability of its new SATA III-based Vector SSD Series featuring the company’s next-generation Indilinx Barefoot 3 controller. OCZ’s worldwide technology hardware and firmware teams developed the new controller silicon and firmware completely in-house to enable full design control over the Vector SSD Series roadmap, while delivering exceptional I/O performance, enhanced reliability and endurance, and a host of differentiated features to empower high performance laptops, desktops, and workstations with superior storage capabilities.
OCZ Vector SSDs provide exceptional input/output operations per second (IOPS) performance and the cutting-edge Barefoot 3 controller consistently delivers superior sustained performance over time regardless of whether the data streams are in compressed or uncompressed formats. As a result, this groundbreaking SSD series provides faster file transfers and boot-ups, and a quicker, more responsive storage experience.
“The development of the Indilinx Barefoot 3 controller architecture is a crowning achievement in our company’s history, being our first controller silicon and firmware completely designed in-house from start to finish using all of the OCZ technology development teams,” said Ralph Schmitt, CEO for OCZ Technology. “These are the first SSD products delivered under the new OCZ and leverages cutting-edge controller technology to deliver a groundbreaking level of sustained performance and reliability for customers seeking a superior SSD for their high performance computing applications.”
The Vector SSD Series is available in 128GB, 256GB, and 512GB capacities, and delivers read bandwidth of up to 550 MB/s, write bandwidth of up to 530 MB/s, random read performance of up to 100,000 IOPS. The Vector’s ultra-slim, 7mm sleek alloy housing supports a wide spectrum of computers including the latest thin form factor notebooks, and each Vector SSD is also bundled with a 3.5-inch desktop adapter bracket and Acronis® True Image™ cloning software to enable quick and easy data transfer from legacy hard disk drive (HDD) storage to high performance Vector SSD storage.\
Endurance was a major priority in the design of the Vector Series, and the highly intelligent Barefoot 3 controller includes an advanced suite of flash management tools that can analyze and dynamically adapt to increasing NAND vulnerabilities as flash cells wear or process geometries get smaller. In this way, the Barefoot 3 controller overcomes the shortcomings associated with MLC NAND flash memory and is specified to deliver 20GB host writes per day for 5 years. This 5-year warranty ensures that Vector SSDs can be reliably used in a wide range of high performance computing environments over an extended lifetime.
Introduction, Specifications and Packaging
OCZ has been in the SSD game for quite some time, and has previously done quite well mixing and matching hardware from other vendors into solutions of their own. It was a good way to put out a large array of products, fitting many a niche for a decent cost. Further, OCZ has always been known as somewhat of an underdog who tailored their parts more towards the power user / tweaker crowd. All of that said, they have been taking steps to become more of a major player in the SSD market, and the fruits of that labor begin their payoff today, with the release of the OCZ Vector:
A new Indilinx Controller?
The Vector comes equipped with a bunch of firsts for OCZ. The controller is OCZ's first 100% in-house part, and has been engineered from the ground up to be as high of a performing part as possible. There has been a paradigm shift within OCZ lately, and the Vector went through a large beta test phase *before* release, as to avoid the need for a series of rapid fire firmware updates just after the product ships. Vector should perform at or near its maximum potential today, not after some firmware updates seen months from now. Here's a look at the controller functional block diagram:
According to a recent press release, OCZ Technology Co. is going to up the Octane ante with a 1TB solid state drive. Coming in at an MSRP of $3,238 USD (approx. 260,000 yen), the SSD features 1TB of synchronous MLC flash, 512MB of DRAM, and an Indilinx Everest controller bundled in a 2.5” form factor.
The SATA 3 (6Gbps) OCT1-25SAT3-1T SSD not only brings gobs of storage, but puts up some respectable performance numbers. It is capable of 460MB/s sequential reads and 330MB/s sequential write speeds. Also, it can deliver a maximum of 24,000 4K read IOPS (input/output operations per second) and 32,000 4K random write IOPS [the translation may be off here, I was expecting to see the higher IOPS reflected as 4K reads and not writes]. Other drive features include TRIP support, ECC (error correction), AES-256 drive encryption, SMART diagnostics, and a MTBF (mean time between failures) of 1,200,000 hours.
The 1TB SSD is slated for a mid-May release and will come with a 3 year warranty. You know, my birthday is coming up in a couple months... (hehe)
Centon Electronics today announced an expansion of their solid state drive lineup with new SATA III offerings. The 2.5” SATA III drives utilize 20nm class MLC (multi level cell) flash memory and a SandForce 2281 SSD controller. They claim that the drives will take full advantage of the extra bandwidth provided by SATA III with read and write speeds of 400 MB per second and 300 MB per second respectively.
According to a chart on Centon’s website, the new SATA III SSDs are part of a new VVS1 series and they come in 60 GB (though this is listed as VS1 series), 120 GB, and 240 GB capacities. The drives support RAID and are rated for a mean time before failure (MTBF) of 2 million+ hours. They further carry a two year warranty. The 240 GB and 120 GB SATA III SSDs are rated at the 400 MB/s and 300 MB/s read and write speeds, but the 60 GB SATA III SSD is only rated at a max of 300 MB/s read and 200 MB/s write. More information can be found on the company's website.Currently, there is no word on pricing or availability. Also, don't forget about our SSD Decoder for all your SSD research!