DWPD – The SSD Guy Blog

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”

Micron Unveils New 5100 Enterprise SSDs

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”

Comparing DWPD to TBW

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”

Seagate’s Big Intro: Four New SSD Families in One Day

Seagate this week updated its SSD portfolio with four new product families and now claims to have the broadest portfolio of storage products in the industry. This announcement squarely places the company in all the key SSD markets: SATA, SAS, and PCIe.

Here’s Seagate’s new lineup:

Seagate 600 6Gb/s SATA, a drive that Seagate calls: “The ultimate laptop upgrade”. The company claims that this is the first Continue reading “Seagate’s Big Intro: Four New SSD Families in One Day”