Update, 4:40 PM EDT: A Western Digital spokesperson confirmed to Ars that the company had replaced the NAND flash and updated the firmware in the WD Blue SN550 as of June 2021 and updated the drive’s datasheet to reflect the changes. “For greater transparency going forward, if we make a change to an existing internal SSD, we commit to introducing a new model number when related published specifications are affected,” a company spokesperson told Ars. “We value our customers and are committed to providing the best possible solutions for their data storage needs.”
Original story, 6:30 a.m. EDT: Western Digital’s WD Blue SN550 budget SSD is a well-reviewed popular NVMe device that has regularly appeared on various sites’ “best SSD” lists since it was released in late 2019. The drive uses a four-lane PCI Express 3.0 interface and was new in that it could outperform SATA SSDs for about the same money.
But that may be about to change, thanks to quiet behind-the-scenes component changes: Chinese site Expreview (via Tom’s Hardware and ExtremeTech) says a newer version of the drive produced in July 2021 was writing data at speeds of around 390MB per second. after the disk cache was full. According to Expreview, that’s about half the speed of older versions of the SN550; Tom’s Hardware measures speeds of approximately 610 MB per second during a sustained write test on the original SN550, so the exact amount of performance drop may vary. Since both the old and new versions of the SN550 use the same SSD controller, it seems likely that the slowdown is caused by inferior NAND flash.
Modern SSDs usually combine a large amount of slower NAND flash (for capacity) and a smaller cache with faster flash memory (for the peak speeds advertised on the box). Depending on the SSD, this cache is designed to support anywhere from a few gigabytes to a few tens of gigabytes of writes before having to fall back on the slower flash. Most of the time, you’ll never notice the drive slowing down because you can’t completely fill the cache by using your computer for basic browsing, office work, or even photo editing.
The people who will notice are professional video editors who regularly export, copy and move huge 4K video files all day long. It’s normal not to get the advertised peak performance from an SSD 100 percent of the time, but a drive that performs significantly worse than it performed in thorough, professional reviews is misleading at best.
Purchasing components from multiple suppliers is common in the manufacture of computers, phones, tablets and the parts that go into them; if you can get something from multiple places, delays or interruptions in production at one supplier are less likely to disrupt the flow of finished products, and competition between suppliers can keep your costs down. But just as important is making sure that the components you buy all perform more or less the same, so you don’t create a “lottery” system where some buyers (and all reviewers) get the “good” version of your product while others get stuck. with worse than expected performance.
SSD makers changing components without updating their model numbers or spec sheets is unfortunately common – Tom’s Hardware has a long list of examples. Sometimes, end users to do take advantage of component changes, such as when SSD manufacturers replace older flash memory with improved flash with better specifications. But in other cases, such as with the SN550 and Adata’s XPG SG8200 Pro, changes made to cut costs or simplify production ultimately come at the expense of performance.
This isn’t the first time in recent history that Western Digital has been caught playing with specs quickly and loosely. The hard drive division has both tampered with the rotational speed of some of its drives and tried to sell slower-performing Shingled Magnetic Recording (or SMR) drives in the WD Red NAS drive lineup, only to come back and reburn them later. .
We contacted Western Digital to follow up on the original reporting; we will update this story as we get new details.