For a long time, The SSD Guy has been talking about Write Amplification without explaining what It is. This post is intended to fix that.
Write amplification is an internal issue for NAND flash SSDs that arises from the way that NAND chips work. It doesn’t exist in standard HDDs, nor did it exist in DRAM SSDs before we had NAND ones. In a nutshell it’s the Continue reading “What is Write Amplification?”
There’s something really odd about Nimbus Data’s colossal 100 terabyte ExaDrive DC SSDs, and it’s not their sheer capacity (although that’s pretty remarkable by itself!) The strange thing is that they can’t be worn out. It’s physically impossible.
At first glance that may seem wrong-headed. NAND flash wears out, and that was the cause of a lot of Continue reading “An SSD You Can’t Wear Out”
For a long time The SSD Guy has meant to write something about the budding use of AI in SSDs. It’s an interesting approach whose time has come.
If you’re not conversant with AI, and maybe find the whole subject to be daunting, don’t worry. AI comes in many forms, and some are very simple. When major Internet firms like Google and Facebook use AI to Continue reading “Using AI to Manage Internal SSD Parameters”
Over the past year there has been a rash of SSD failures unmatched by any prior year. This came to a head a month ago when Apple’s M1 Mac started to show undue SSD wear. It seems that people trapped at home and working remotely have taken up new habits on their notebook PCs (most of which now use SSDs) and these habits are causing their SSDs to wear out faster than they have in other, more normal years.
The “Work from Home” phenomenon has not only caused Continue reading “Failures Plague SSDs”
I was recently reminded of a presentation made by GoDaddy way back in the 2013 Flash Memory Summit in which I first heard the statement: “Failure is not an option — it is a requirement!” That’s certainly something that got my attention! It just sounded wrong.
In fact, this expression was used to describe a very pragmatic approach the company’s storage team had devised to determine the exact maximum load that could be supported by any piece of its storage system.
This is key, since, at the time, GoDaddy claimed to be the world’s largest web hosting service with 11 million users, 54 million domains registered, over 5 million hosting accounts, with a 99.9% uptime guarantee (although the internal goal was 99.999% – five nines!)
The presenters outlined four stages of how validation processes had Continue reading “Failure is Not an Option — It’s a Requirement!”
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”
A new and highly-efficient error correction scheme has recently been revealed by a joint university research team. The SSD Guy has learned that this largely-overlooked research, performed by a cross-university team from University of North by Northeast Wales in the UK (UN-NeW) and Poland’s Trzetrzelewska University, could bring great economies to SSD manufacturers and all-flash array (AFA) companies.
Dr. Peter Llanfairpullguryngyllgogeryohuryrndrodullllantysiliogogogoch of UN-NeW, who generally shortens his name to Llanfairpullguryngyll and Dr. Agnieszka Włotrzewiszczykowycki of Trzetrzelewska University have determined that today’s more standard ECC engines can be dramatically improved upon to both increase available storage for a given price while accelerating throughput. This is achieved through the use of new and highly complex algorithms that differ radically from current ECC approaches that are simply linear improvements upon past algorithms.
According to Dr. Włotrzewiszczykowycki: “The beauty of semiconductors is that Moore’s Law not only allows Continue reading “Extreme ECC Enables Big SSD Advances”
On January 12 IBM announced some very serious upgrades to its DS8000 series of storage arrays. Until this announcement only the top-of-the-line model, the IBM System Storage DS8888, was all-flash while the less expensive DS8886 and DS8884 sported a hybrid flash + HDD approach. The new models of the DS8886 and DS8884 are now also all-flash.
But that’s not all: Every model in this product family has been upgraded.
The original DS8000 systems used a module called the High Performance Flash Enclosure (HPFE) for any flash they included, while these newer models are all based on HPFE Gen 2. While the original HPFE was limited to a maximum capacity of 24TB in a 1U space, the larger 4U HPFE Gen 2 can be configured with as much as 153.6 TB, for more than six times the storage of the previous generation. By making this change, and by optimizing the data path, the Gen 2 nearly doubles read IOPS to 500K and more than triples read bandwidth to 14GB/s. Write IOPS in the Gen 2 have been increased 50% to 300K, while write bandwidth has been increased by nearly 4x to 10.5GB/s .
This kind of performance opens new Continue reading “IBM Upgrades DS8000 Series: All Models are now All-Flash”
Micron has announced a new line of Enterprise SSDs that it has named the 5100 family. The three members of the family are designated by different suffixes: 5100 ECO, 5100 PRO, and 5100 MAX, as listed in the table below.
The three models support the same maximum read IOPS performance, but have a wide range of write IOPS figures, endurance (measured in DWPD = Drive Writes per Day), and maximum capacities.
All of these SSDs are based on Micron’s 3-bit 3D NAND. Micron has been aggressively ramping its 3D NAND technology since it began shipments in earnest last June.
The three SSD models are designed using the same fundamental firmware architecture, which Micron has named FlexPro, to yield consistent performance and reliability across the family, and with the hopes that customers will be able to qualify all three models in a single effort, which would provide one more reason for users to source their Continue reading “Micron Unveils New 5100 Enterprise SSDs”
A couple of specifications for SSD endurance are in common use today: Terabytes Written (TBW) and Drive Writes Per Day (DWPD). Both are different ways to express the same thing. It seems that one vendor will specify endurance using TBW, while another will specify DWPD. How do you compare the two?
First, some definitions. “Terabytes Written” is the total amount of data that can be written into an SSD before it is likely to fail. “Drive Writes Per Day” tells how many times you can overwrite the entire capacity of the SSD every single day of its usable life without failure during the warranty period. Since both of these are guaranteed specifications, then your drive is most likely to last a lot longer than the number given by the SSD’s maker.
To convert between the two you must know the disk’s capacity and the warranty period. If drive maker gives you TBW but you want to know DWPD you would approach it Continue reading “Comparing DWPD to TBW”