Client SSDs

The Memory/Storage Hierarchy

Memory/Storage ThumbnailIt recently dawned on me that one of the charts that I most frequently use in my presentations has never been explained in The SSD Guy blog.  This is a serious oversight that I will correct with this post.

The Memory/Storage Hierarchy (also called the Storage/Memory Hierarchy, depending on your perspective) is a very simply way to explain why there are multiple memory and storage types within a system: Why is there a cache memory, or a DRAM, or an HDD?  The simple answer is that you can improve the system’s cost/performance ratio of you break the system down into an appropriate mix of fast & slow, expensive & cheap memory or storage.

To explain this I go way back to the 1960s and review the concept of “Virtual Memory”.  This concept was first commercialized by computer maker Burroughs, although it was first implemented by the University of Manchester in England.  The basic concept was to provide programmers with an extraordinarily large memory in which to run their programs by fooling the program into thinking that the memory was as large as the magnetic disk.

I actually look at it from Continue reading

Start-Up Fadu Launches New SSD Controller

Fadu, a startup out of Korea, made a big  splash at the Flash Memory Summit to announce its new NVMe SSD controllers that don’t compromise speed to achieve low-power operation.

The company’s products are focused on quality of service (QOS) in enterprise-style 24/7 workloads with the aim of enabling the transition to NVMe in Enterprise and Hyperscale data centers, the fastest-growing segments in the SSD market.  Some readers may recall that Fadu won the 2018 FMS Best-of-Show award in the “Most Innovative Flash Memory Technology” category for an earlier generation of products.

The company’s founding team comes from Samsung and Hynix with a CEO (Jihyo Lee) from Bain Capital.  Lee gave a keynote address at the Flash Memory Summit simply titled: “Enterprise SSD: The Future”

The new SSD controller, Annapurna, is a Continue reading

What is an SSD Trim Command?

TrimmerAlthough the Trim command has been defined for nearly a decade, for some reason I have never written a post to explain it.  It’s time for that to change.

Trim is something that was never required for HDDs, so it was a new command that was defined once SSDs became prevalent.  The command is required because of one of those awkward encumbrances that NAND users must accommodate: Erase before write.

NAND flash bits cannot be altered the same way as an HDD.  In an HDD a bit that’s currently set to a “1” can be re-written to a “0” and vice versa.  Writing a bit either way takes the same amount of time.  In NAND flash a 1 can be written to a zero, but the opposite is not the case.  Instead, the entire block (4-16k bytes) must be erased at once, after which all bits are set to a 1.  Once that has been done then zeros can be written into that block to store data.  An erase is an excruciatingly slow operation, taking up to a half second to perform.  Writes are faster, but they’re still slow.

Let’s say that a program needs to Continue reading

Are SSDs Approaching Price Parity with HDDs?

July 2007 HDD vs SSD Price AnalysisA recent Storage Newsletter article argues that SSD prices are approaching HDD prices, and that the gap has narrowed to only a 2.7 times difference.

Upon closer inspection, though, the reader will note that this is only true at lower capacities.  The narrowing price gap at lower capacities has always existed in this market.  The SSD Guy was making that  argument back in 2007!

This post’s graphic shows a chart from the first report ever published by Objective Analysis over a decade ago: The Solid State Disk Market – A Rigorous Look.

The point of this chart was to illustrate that, at low capacities, SSDs are cheaper, while at higher capacities HDDs provide lower-priced storage.

The concept is simple: It’s uneconomical for an Continue reading

Storage Visions Conference Coming Oct 22

Once again The SSD Guy will be playing a part in the annual Storage Visions conference which has been moved this year to the Santa Clara Hyatt Hotel adjacent to the Santa Clara Convention Center.  It’s now a 2-day conference (October 22-23) and has an agenda packed with interesting subjects, speakers, and panelists.

Storage Visions’ mission is to bring together the vendors, end users, researchers and visionaries that will meet growing demand for digital storage for the “coming data tsunami.”

I will moderate a panel on an exciting new technology that is currently known by a few different names, including “In-Situ Processing,” “Computational Storage,” and “Intelligent SSDs” (iSSD).  It’s a kind of SSD that uses internal processing to reduce the amount of data traffic between the server and storage.  This helps get past an issue that plagues many applications which spend more time and energy moving data back and forth than they do actually processing that data.

The panel, at 8:15 Monday morning, October 22, is Continue reading

Podcast: Flash Memory Summit

GreybeardsThose of you who enjoy listening to podcasts may want to hear Ray Lucchesi (Silverton Consulting) and Howard Marks (Deep Storage) interview The SSD Guy for their series “Greybeards on Storage.”

This interview is their 70th episode covering the world of storage.  These guys do a fantastic job of probing this industry with great enthusiasm and insight.

This episode is a 42-minute compendium of the sights and goings-on at last August’s Flash Memory Summit along with a number of side trips into the world of SSDs and memory chips.  It’s not strictly structured, and not strictly serious, but just three industry insiders having a lot of fun sharing their observations.

Some of the broad range of subjects that we Continue reading

The Micron QLC SSD – No Surprises Here

Progression of SSDsLast Monday, May 21, Micron introduced the industry’s first QLC SSD for enterprise applications.  Micron’s press release is HERE.

Although this is a laudatory feat, the industry has been headed in this direction for a number of years.  In fact, this was the subject of a presentation that I made to the Storage Networking Industry Association (SNIA) during its Winter Symposium in January 2014.

The slide in which I discussed this appears as this post’s graphic.  (Click on it to see a larger rendition.)  This table attempted to illustrate that all SSDs were headed towards TLC (and implicitly QLC) over the long term despite the fact that naysayers persistently argued that this could never happen.  It looks at attitudes over history and considers the fact that things that the industry said could “Never” happen ended up eventually becoming the mainstream technology.

Since I live, eat, and breathe Continue reading

NVDIMM Report Now Available

I am proud to share the release of a new Objective Analysis report detailing the nonvolatile dual inline memory module (NVDIMM) market.  Titled: “Profiting from the NVDIMM Market,” this report explains the What, How, Why, & When of NVDIMMs, and forecasts the market through 2021.

Readers are aware that I have been watching this market for some time, and never really know whether I should post about NVDIMMs in The SSD Guy or in The Memory Guy, since the boundary between memory and storage is bridged by these products.  My solution: publish posts about this report in both blogs!

According to the Objective Analysis NVDIMM market model the NVDIMM market can be expected to reach nearly 12 million units by 2021, representing a 105% average annual growth rate.  The forecast methodology used for this model has provided some of the semiconductor business’ most consistently-accurate forecasts.  The report, which includes this forecast, was the result of thorough research into the technology and the circumstances that led to the introduction of NVDIMMs, NVDIMM vendor and user interviews, and briefings from those standards bodies that are diligently working to provide timely support for this new technology.

This in-depth 80-page analysis explores the Continue reading

Comparing SSDs to Tomatoes

TomatoA few years ago The SSD Guy posted an analogy that Intel’s Jim Pappas uses to illustrate the latency differences between DRAM, an SSD, and an HDD.  If we look at DRAM latency to be a single heartbeat, then what happens when we scale that timing up to represent SSDs and HDDs?  How many heartbeats would it take to access either one, and what could you do in that time?

I still think it’s a pretty interesting way to make all these latency differences easier to understand.

Just recently I learned of a Rich Report video of a 2015 presentation in which Micron’s Ryan Baxter uses a different and equally interesting analogy based on tomatoes.

Tomatoes aren’t the first thing that comes to my mind when I think about SSDs, but this video may change my way of thinking!

The tomato slide, 9:30 into the presentation, is Continue reading

Comparing Wear Figures on SSDs

DWPD TBW GB/Day TriangleI have been receiving questions lately from people who are puzzled when companies use different parameters than their competitors use to specify the endurance of their SSDs.  How do you compare one against the other?  Some companies even switch from one parameter to another to define the endurance of different SSDs within their product line.

I have found that Intel uses three different endurance measures for its products: DWPD (drive writes per day), TBW (terabytes written), and GB/day.

There’s not any real difference between any of these measures – each one is one way of stating how many times each of the SSD’s locations can be overwritten before the drive has gone past its warrantied life.

The relationships between these three measures are illustrated in this post’s graphic.  You can click on it to see an expanded version.  It’s all pretty simple.  We’ll spell out the relationships in detail below, but in brief, if you want to compare Continue reading