New Samsung 840 EVO employs TLC and pseudo-SLC TurboWrite cache

Subject: Storage | July 18, 2013 - 01:12 AM |
Tagged: tlc, ssd, slc, sata, Samsung, cache, 840 evo

Samsung's release of the 840 EVO earlier today likely prompted some questions, such as what type of flash does it employ and how does it achieve such high write speeds. Here is the short answer, with many slides in-between, starting off with the main differences between the 840 and the 840 EVO:

DSC04627.JPG

So, slightly increased specs to help boost drive performance, and an important tidbit in that the new SSD does in fact keep TLC flash. Now a closer look at the increased write specs:

DSC04633.JPG

Ok, the speeds are much quicker, even though the flash is still TLC and even on a smaller process. How does it pull off this trick? Tech that Samsung calls TurboWrite.

DSC04637.JPG

A segment of the TLC flash is accessed by the controller as if it were SLC flash. This section of flash can be accessed (especially written) much faster. Writes are initially dumped to this area and that data is later moved over to the TLC area. This happenes as it would in a normal write-back cache - either during idle states or once the cache becomes full, which is what would happen during a sustained maximum speed write operation that is larger than the cache capacity. Here is the net effect with the cache in use and also when the cache becomes full:

DSC04638.JPG

For most users, even the smallest cache capacity will be sufficient for the vast majority of typical use. Larger caches appear in larger capacities, further improving performance under periods of large write demand. Here's the full spread of cache sizes per capacity point:

DSC04639.JPG

So there you have it, Samsung's new TurboWrite technology in a nutshell. More to follow (along with a performance review coming in the next few days). Stay tuned!

Big Flashy news from Samsung

Subject: General Tech | April 11, 2013 - 02:38 PM |
Tagged: tlc, Samsung, flash memory, 10nm

A process shrink to 10nm wasn't enough for Samsung, they also doubled the density of their MLC flash storage to 128Gbits at a physical size of 170.6mm2.  They claim write speeds of up to 18MB/sec and 400Mbit/s bandwidth through their toggle interface.  Even better news for consumers is that this should be even cheaper than current MLC flash which will help continue to drive the price of SSDs down.  Samsung didn't tell The Inquirer when we can expect to see these in devices but it should not be too long from now that we are doing longevity testing on this new Flash.

samsungchips.jpg

"MEMORY MAKER Samsung has announced that it is producing 128Gbit 3-bit multi-level cell (MLC) NAND flash chips for solid-state disk (SSD) drives"

Here is some more Tech News from around the web:

Tech Talk

Source: The Inquirer
Subject: Editorial, Storage
Manufacturer: Various
Tagged: tlc, ssd, slc, mlc, endurance

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 Slashdotthis 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:

writeamplification2.png

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:

flash-1.png

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:

flash-2.png

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.

Samsung 840 Series gives SSD fans a little TLC

Subject: Storage | January 3, 2013 - 03:22 PM |
Tagged: tlc, Samsung 840, 500gb, ssd

As the lifespan of flash memory in SSDs has become a topic of concern for many users, it is nice to see that the Samsung 840 500GB has a lifespan of some 14 years assuming a daily write load of 10GB.  Since most users do not write 10GB to a drive day in and day out, that estimate is probably on the low end.  If that doesn't have you excited then consider the cost of the drive, at $350 it is much lower than the $1/GB mark most other SSDs are at.  There are some trade offs however, [H]ard|OCP saw comparatively slow extended write speeds though the read speeds were higher than the 256GB model.  When you consider this drive do keep in mind that it is still going to be faster than a platter drive even when it is working on a task that other SSDs might do slightly faster.

H_840_500.jpg

"Samsung has released the first TLC NAND equipped SSDs into the market, creating the lowest price points we have witnessed for SSDs bringing large capacity SSDs within reach for average users. Today we test the 500GB TLC Samsung 840 Series SSD to test the performance in steady state of a large capacity TLC Solid State Drive."

Here are some more Storage reviews from around the web:

Storage

Source: [H]ard|OCP

Samsung's new 21nm Toggle TLC Flash based Series 840 SSDs

Subject: Storage | November 20, 2012 - 03:48 PM |
Tagged: Samsung, 840, tlc

As part of their review of the Samsung 840 250GB SSD, The Tech Report covers the specifics of the TLC flash memory which is used in the 840 series as opposed to the MLC we saw in the 830 series.   As well they show off some of the capabilities of the control software, which Samsung has dubbed the SSD Magician utility.  Of course from there the benchmarking begins which showed performance continually below the similarly priced 830 series which hurts the new SSDs on the price to performance chart.  Overall they are hard pressed to recommend the drive over the previous models, not only because of the performance but also the shortened lifespan of TLC flash.  As that flash technology matures we may see those concerns fade, as Allyn pointed out in his review.

TR_box.jpg

"Samsung's 840 Series SSD combines a next-gen fabrication process with an extra bit per cell to lower the cost per gigabyte. We take a closer look at the implications and see how the drive stacks up against the competition."

Here are some more Storage reviews from around the web:

Storage

Subject: Storage
Tagged: tlc, ssd, Samsung, pro, mdx, 840

Introduction, Specifications and Packaging

Introduction

Last week, Samsung flew myself and a few of my fellow peers in the storage review community out to Seoul, Korea. The event was the 2012 Samsung SSD Global Summit:

120924-104020-4.28.jpg

At this event, Samsung officially announced their new 840 Pro, which we were able to obtain early under NDA and therefore publish in concert with the announcement. The 840 Pro was largely an incremental inprovement over their 830 Series. Newer, faster flash coupled with a higher clocked controller did well to improve on an already excellent product.

121002-220858-6.35.jpg

As the event closed, we were presented with the second model of the lineup - the 840. This model, sans the 'Pro' moniker, is meant more for general consumer usage. The first mass marketed SSD to use Triple Level Cell (TLC) flash, it sacrifices some write speed and long-term reliability in favor of what should become considerably lower cost/GB as production ramps up to full capacity. TLC flash is the next step beyond MLC, which is in turn a step after SLC. Here's a graphic to demonstrate:

slc-mlc-tlc-glass.jpg

Read on for the full review!

Podcast #220 - Samsung 840 Pro SSD, a 1500W PSU from EVGA, AMD GPU leaks, and more!

Subject: General Tech | September 27, 2012 - 01:46 PM |
Tagged: tlc, ssd, Sea Islands, Samsung, PSU, podcast, nvidia, IOPS, Intel, evga, amd, 840 pro, 840, 1500W

PC Perspective Podcast #220 - 09/27/2012

Join us this week as we talk about the Samsung 840 Pro SSD, a 1500W PSU from EVGA, AMD GPU leaks, and more!

You can subscribe to us through iTunes and you can still access it directly through the RSS page HERE.

The URL for the podcast is: http://pcper.com/podcast - Share with your friends!

  • iTunes - Subscribe to the podcast directly through the iTunes Store
  • RSS - Subscribe through your regular RSS reader
  • MP3 - Direct download link to the MP3 file

Hosts: Ryan Shrout, Josh Walrath, Jeremy Hellstrom, and Allyn Malvantano

This Podcast is brought to you by MSI!

Program length: 1:07:28

Podcast topics of discussion:

  1. Week in Reviews:
    1. 0:02:55 Samsung 840 Pro 512GB SSD
    2. 0:17:50 EVGA SuperNOVA 1500 watt PSU
  2. 0:23:20 This Podcast is brought to you by MSI!
  3. News items of interest:
    1. 0:24:05 Raspberry Pi to get a Turbo button?
    2. 0:26:30 Looking for a $1200 Muderbox?
    3. 0:29:05 GLOBALFOUNDRIES goes 3D with FinFET
    4. 0:41:10 AMD Sea Islands GPU leaks
    5. 0:46:00 Maingear launches an All-in-One with a GTX 680
    6. 0:50:50 Catalyst 12.9 Released
    7. 0:55:20 Long term storage?
  4. Closing:
    1. 0:57:30 Hardware / Software Pick of the Week
      1. Ryan: AVADirect Mini-ITX Gaming System
      2. Jeremy: and now I can't find the smegging disks
      3. Josh: A fun barebones- not perfect, but cheap!
      4. Allyn: Samsung 830 deals! (anywhere you can get 'em)
  1. 1-888-38-PCPER or podcast@pcper.com
  2. http://pcper.com/podcast
  3. http://twitter.com/ryanshrout and http://twitter.com/pcper
  4. Closing/outro
  5.  

OCZ wraps both its ARMs around a new SSD controller and gives it a little TLC

Subject: General Tech | July 26, 2011 - 12:03 PM |
Tagged: ssd, ocz, arm, tlc, sata 6Gps, Indilinx Everest

OCZ is never satisfied with the performance of their SSDs in general and their controllers specifically.  After purchasing Indilinx to ensure that their controllers would be of high quality and designed to OCZ's specific needs, they've now been pushing Indilinx to improve on their controllers.  That has lead to Everest, which has a dual core ARM processor and 400MHz DDR3 cache that can support up to 512MB.  The controller is optimized for 8K writes which is perfect for the current flash utilized in SSDs.  OCZ has also optimized the flash memory, developing Triple Level Cell (TLC) which has three layers as opposed to MLC which sports two.  The controller will be backwards compatible, which is a good idea if OCZ wants to license the controller to other manufacturers, which makes sense as Everest should hit 200MT/s as compared to SandForce's current 166MT/s.  There is more that this controller can do, click on over to The Register to read about it.

Holysh.jpg

"OCZ is sampling a new flash controller that gives a picture of future solid state drives.

The company bought Indilinx for its solid state drive (SSD) controller technology in March this year and has now unveiled the Indilinx Everest controller platform.

It has a 6Gbit/s SATA III interface, a dual-core ARM processor and a number of enticing features, such as 3-bit multi-level cell (MLC) support. This is going to be called TLC, for triple-level cell, to distinguish it from today's MLC, which is 2-bit MLC."

Here is some more Tech News from around the web:

Tech Talk

Source: The Register

Next gen SSD controllers pushing for TLC flash

Subject: Storage | April 27, 2011 - 10:06 PM |
Tagged: tlc, ssd, slc, ocz, mlc, flash

A while back, Intel and Micron jointly announced the beginnings of 20nm flash memory production, promising a 50% increase in die count per wafer (or a 50% reduction in per die production cost, depending on how you slice it). This shrink only did just that - shrink the die. Capacity remained at 64Gbit (8GB).

A few days ago IMFT also announced another way to shrink that die, but this time keeping with the now 'old' 25nm process. It turns out they have refined 25nm to the point where consumer-grade TLC flash can be produced. TLC is Triple-Level-Cell. While SLC (Single) holds 1 bit per cell, and MLC (Multi) holds two, TLC holds 3 bits per cell. Compared to the MLC 25nm dies, this gives a capacity increase without changing much else. IMFT, however, is happy with the 8GB 'sweet spot', so instead of jumping to a 12GB die of the same physical size, they are opting to instead shrink the current 25nm die to 131mm^2.

INTC_Micron_TLC_NAND_350.jpg

25nm TLC die, same 8GB capacity, but less area than the 25nm MLC die.

This gives Intel and Micron two options for ultimately reducing the price of flash - either by shrinking the process and getting more 8GB MLC dies out of a 20nm wafer, or by squeezing more bits into each cell of existing 25nm flash.

This is good stuff. Let's hope it gets even more SSD's into even more machines this holiday season.