A new bug may be present in the firmware of some Samsung SSDs. An engineer from search provider Algolia has written up a blog post detailing his team’s saga of troubleshooting data corruption in some of their servers. Ultimately, Algolia narrowed down the problem to an apparent bug in the TRIM implementation used in Samsung drives.

This TRIM bug can cause affected drives to zero out 512-byte blocks of data in incorrect, seemingly random locations. For larger files, the net result is corrupted data, while smaller files can be overwritten entirely.

Algolia ruled out other causes for the corruption by carrying out a thorough investigation of several other layers in their service’s stack, including Linux’s RAID implementation, kernel, and filesystem. The company also found that servers running Intel drives were unaffected by this issue.

The affected drives in use at Algolia are:

Samsung MZ7WD480HCGM-00003 (model SM843TN)

Samsung MZ7GE480HMHP-00003 (model PM853T)

Samsung MZ7GE240HMGR-00003 (model PM853T)

Samsung SSD 840 PRO Series

Samsung SSD 850 PRO 512GB

If Algolia’s determinations are correct, this problem is potentially quite serious. It also wouldn’t be the first SSD-related black eye for Samsung, which recently issued two separate updates to remedy the read slowdowns we’ve seen with the 840 EVO SSD.

We’ve brought Algolia’s claims to Samsung’s attention, and we’ll update this post with more information as it becomes available. Thanks to our shy anonymous tipster for the heads-up.