Another Windows update, another round of users complaining about crashes and bugs. While hardly news, this time around the fault is very specific but also very annoying, and it concerns Western Digital SSDs, specifically its SN770 and SN580 models. It seems that these drives just aren't ready for the 24H2 update and the result is a glut of crashes and infamous Blue Screens of Death (BSODs).
All of these troubles were flagged up by SN770/SN580 owners on Western Digital's community forums (via TechSpot). It looks like the problem revolves around something called the Host Memory Buffer (HMB). All SSDs store a map of where data is located within its flash memory chips and this constantly gets updated, as information gets deleted and added.
Some SSDs have a single DRAM module on them and store the map in that, but many gaming SSDs are DRAM-less (to reduce the price tag) and instead, store this map in a little bit of the PC's system memory. This is called the HMB and without it, performance takes a hit when doing lots of little writes and erases.
From what WD SSD owners have been saying, it would seem that the WD Black SN770 and Blue SN580 stick to a maximum HMB size of 64 MB but in the 24H2 update, Windows increases this to 200 MB. The SSD's firmware doesn't like this figure and the result is all the errors.
Current solutions involve delving into Window's registry and heading to the Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorPort section. For SN770/SN850 owners, there should be an entry labelled HMBAllocationPolicy and all one needs to do is set the value to zero and then reboot. This disables the use of the HMB but it does apparently cure the problem.
However, other forum visitors suggest a value of 2 works for them. Some users just used Windows' rollback feature to return the operating system to its previous 23H2 status. The real solution, of course, requires a fix from Microsoft and/or an updated firmware from Western Digital for those SSDs.
What's interesting is that there is a large number of other SSD models out there that also use a 64 MB size HMB but as of yet, I've not seen any complaints about Windows bailing out on those drives. I'm not suggesting this is all Western Digital's fault because one thing we don't know is if Microsoft made it clear to all SSD vendors that the default HMB size would be changed in 24H2.
The 24H2 update is being slowly rolled out at the moment, so not everyone has the choice to install it yet. But if you do own a WD SN770 or SN580 SSD, then I strongly recommend you wait until Western Digital releases a new firmware fix for its drives.
