At last month’s SNIA Persistent Memory Summit Oracle presenter Jia Shi, Sr. Director of Exadata Development, shared some statistics on the Exadata system’s history over the past ten years. (Click on the graphic to the left to see the timeline.) The speaker highlighted the fact that the system’s I/O performance has grown from 0.05 million IOPS ten years ago to 16 million IOPS today, a 320X improvement! Shi said that Continue reading “Does Persistent Memory Improve Performance? Ask Oracle!”
The Micron QLC SSD – No Surprises Here
Last 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 “The Micron QLC SSD – No Surprises Here”
Comparing SSDs to Tomatoes
A 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 SSDs to Tomatoes”
An NVDIMM Primer (Part 2 of 2)
This post is the second of a two-part SSD Guy series outlining the nonvolatile DIMM or NVDIMM. The first part explained what an NVDIMM is and how they are named. This second part describes the software used to support NVDIMMs (BIOS, operating system, and processor instructions) and discusses issues of security.
Today’s standard software boots a computer under the assumption that the memory at boot-up contains random bits — this needed to be changed to support NVDIMMs. The most fundamental of these changes was to the BIOS (Basic I/O Subsystem), the code that “wakes up” the computer.
The BIOS is responsible for detecting all of the computer’s hardware and installing the appropriate drivers, after which it loads the bootstrap program from the mass storage device into the DRAM main memory. When an NVDIMM is used the BIOS must Continue reading “An NVDIMM Primer (Part 2 of 2)”
An NVDIMM Primer (Part 1 of 2)
NVDIMMs are gaining interest lately, so The SSD Guy thought it might be worthwhile to explain both what they are and how NVDIMM nomenclature works.
As I was writing it I noticed that the post got pretty long, so I have split it into two parts. The first part explains what an NVDIMM is and defines the names for today’s three kinds of NVDIMM. The second part tells about software changes used to support NVDIMMs in BIOS, operating systems, and even processor instruction sets. It also discusses the problem of security.
In case the name is unfamiliar, NVDIMM stands for “Nonvolatile Dual-Inline Memory Module.” Standard computer memory – DRAM – is inserted into the system in the DIMM form factor, but DRAM loses its data when power is removed. The NVDIMM is nonvolatile, or persistent, so its data remains intact despite a loss of power. This takes some effort and always costs more for reasons that will be explained shortly.
Although might seem a little odd to discuss memory in a forum devoted to SSDs, which are clearly storage, the NVDIMM is a storage device, so it rightly Continue reading “An NVDIMM Primer (Part 1 of 2)”
Comparing Wear Figures on SSDs
I 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 “Comparing Wear Figures on SSDs”
3D XPoint Memory at the Storage Developer’s Conference
This Sunday (Sept. 20, 2015) I will be presenting my company’s findings on the 3D XPoint memory that was introduced by Intel and Micron in July. I will be speaking at the Storage Networking Industry Association (SNIA) Storage Developer Conference (SDC) Pre-Conference Primer. You can click the name to be taken to the agenda.
This won’t be the only talk about persistent memory technology at the conference. Prior to my presentation storage consultants Tom Coughlin and Ed Grochowski will give an overview of advances in nonvolatile memories, and following my presentation will be two Intel talks.
Intel will be covering this new technology a lot during the conference. Of a total of 120 presentations at the conference and pre-conference primer, Intel will be presenting nine, seven of which directly name persistent memory or nonvolatile memory in the title. Other firms will also be talking about NVM: AgigA, Calypso, HP, Pure Storage, and SMART Modular. Even Microsoft alludes to it in a couple of its presentation titles. Persistent memory is a hot issue.
So, the question for readers of The SSD Guy blog is: “Will this do away with SSDs?”
This is a question that was Continue reading “3D XPoint Memory at the Storage Developer’s Conference”
Understanding Storage Delays
Jim Pappas of Intel, a fellow member of SNIA (the Storage Networking Industry Association) shared a really intuitive way to understand storage delays at the last Storage Developer Conference (SDC). It’s very simple. First consider these two facts:
- The difference between the speed of system memory and that of a hard disk drive (HDD) is roughly 6 orders of magnitude, or 1 million times
- SSDs split the gap. An SSD is about 1,000 times faster than an HDD, and is about 1,000 times slower than system memory. Memory access times are measured in nanoseconds (ns), SSDs in microseconds (µs) and HDDs in milliseconds (ms)
The problem with understanding this (ns, µs, ms) is that Continue reading “Understanding Storage Delays”
Intel Intros Fast Datacenter SATA SSD
Today Intel announced a new SATA III SSD, the DC S3700 Series. The new product is fast, supporting 75,000 random 4K read IOPS and 36,000 random 4K write IOPS. Average read latency is 45microseconds (µs) with writes averaging 65µs. Sustained sequential reads are 500 megabytes/sec with sustained sequential writes at 460. The read performance of this SSD, although a SATA device, is twice that of Intel’s 710 PCIe SSD announced in April, and writes are a full 15 times faster. Intel calls this performance: “Scary fast!”
Intel says this device is its best Continue reading “Intel Intros Fast Datacenter SATA SSD”
19nm & 20nm SSDs Arrive!
SSD-watchers have expressed some concern over the last few years that SSDs cannot be manufactured using advanced NAND flash process geometries. This is because these parts have lower endurance and a larger number of bit errors than NAND made using less-advanced processes – the tighter the process, the shorter the flash’s life, and the more errors it will have.
Fortunately these concerns seem to be Continue reading “19nm & 20nm SSDs Arrive!”