Silent changes to Western Digital’s budget SSD may lower speeds by up to 50% [Updated]

Enlarge / Newer versions of Western Digital's WD Blue SN550 may perform worse than older ones. (credit: Western Digital)

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 beginning in June 2021 and updated the drive's data sheet 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 whenever any related published specifications are impacted," 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 am EDT: Western Digital's WD Blue SN550 budget SSD is a well-reviewed popular NVMe device that has regularly shown up on various sites' "best SSD" lists since it was released at the tail-end of 2019. The drive uses a four-lane PCI Express 3.0 interface and was novel for being able to perform better than SATA SSDs for about the same amount of money.

But that may be changing, thanks to quiet behind-the-scenes component changes: Chinese site Expreview (via Tom's Hardware and ExtremeTech) says that a newer version of the drive manufactured in July 2021 was writing data at speeds of about 390MB per second after the drive's cache had filled up. According to Expreview, that's about half the speed of older versions of the SN550; Tom's Hardware measured speeds of about 610MB per second during a sustained write test on the original SN550, so the exact amount of performance degradation may vary. Because both the old and new versions of the SN550 use the same SSD controller, it seems likely that the slowdown is being caused by inferior NAND flash.

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