Silicon Motion's early reassurance — that “so far, none of our controllers are affected” by the Windows 11 update that has been making some NVMe drives disappear under sustained writes — is an encouraging datapoint, but it is provisional and incomplete: the incident remains an active, cross‑stack investigation involving Microsoft, controller vendors (notably Phison), SSD manufacturers, and community test benches, and the safest posture for users and IT teams remains conservative risk management (backups, hold heavy writes, and wait for SKU‑level firmware confirmations). (bleepingcomputer.com)
In mid‑August 2025 Microsoft shipped the combined servicing stack and cumulative update for Windows 11 (24H2), identified in community coverage as KB5063878 (OS Build 26100.4946). Days after the roll‑out, multiple independent test benches and community researchers reported a reproducible failure profile: under sustained sequential writes (commonly reproduced at roughly 50 GB of continuous writing on drives that were already moderately full), some NVMe SSDs became unresponsive, vanished from Windows device inventories, and in a subset of cases retained corrupted or unreadable SMART data and filesystem state. Reboots sometimes restored access; other times drives remained inaccessible and required vendor intervention. (support.microsoft.com, tomshardware.com)
The community‑led reproductions highlighted an apparent over‑representation of Phison‑based and some DRAM‑less controllers among affected drives, prompting Phison to publicly acknowledge it was investigating “industry‑wide effects” and to cooperate with Microsoft and partners. At the same time, multiple labs reported that non‑Phison devices also failed in isolated runs, pointing to a likely host‑to‑controller interaction rather than a single, universal firmware defect. (bleepingcomputer.com)
Into that unsettled context came the Silicon Motion reply relayed in forum threads and specialist collations: according to the forum message, Silicon Motion had not observed the failure in their controllers to date. That reply, while welcome to owners of Silicon Motion‑based drives, is an informal signal — useful but not definitive — because vendor advisories normally require SKU‑level validation and publication of affected firmware IDs to be actionable for enterprise and cautious consumers.
Users and administrators should monitor official vendor support pages and the Windows update health channels for formal advisories and firmware downloads. Treat community reassurances as useful lead indicators, not as substitutes for vendor‑validated confirmation.
Conclusion: Silicon Motion's message provides a welcome early signal, but it does not close the case. Robust backups and measured, evidence‑based patch management remain the best protection while the industry works through cross‑stack telemetry and publishes definitive firmware and OS mitigations.
Source: Club386 Silicon Motion says none of its SSD controllers are affected by the Windows 11 death bug, so far | Club386
Background / Overview
In mid‑August 2025 Microsoft shipped the combined servicing stack and cumulative update for Windows 11 (24H2), identified in community coverage as KB5063878 (OS Build 26100.4946). Days after the roll‑out, multiple independent test benches and community researchers reported a reproducible failure profile: under sustained sequential writes (commonly reproduced at roughly 50 GB of continuous writing on drives that were already moderately full), some NVMe SSDs became unresponsive, vanished from Windows device inventories, and in a subset of cases retained corrupted or unreadable SMART data and filesystem state. Reboots sometimes restored access; other times drives remained inaccessible and required vendor intervention. (support.microsoft.com, tomshardware.com)The community‑led reproductions highlighted an apparent over‑representation of Phison‑based and some DRAM‑less controllers among affected drives, prompting Phison to publicly acknowledge it was investigating “industry‑wide effects” and to cooperate with Microsoft and partners. At the same time, multiple labs reported that non‑Phison devices also failed in isolated runs, pointing to a likely host‑to‑controller interaction rather than a single, universal firmware defect. (bleepingcomputer.com)
Into that unsettled context came the Silicon Motion reply relayed in forum threads and specialist collations: according to the forum message, Silicon Motion had not observed the failure in their controllers to date. That reply, while welcome to owners of Silicon Motion‑based drives, is an informal signal — useful but not definitive — because vendor advisories normally require SKU‑level validation and publication of affected firmware IDs to be actionable for enterprise and cautious consumers.
What Silicon Motion actually said — and what that means
- The company's reported message, as relayed through community forums and specialist sites, was: “so far, none of the SMI controllers have experienced such a problem.” That wording is time‑boxed and observational: it states a current absence of reported incidents across the datasets Silicon Motion has seen, not an absolute guarantee of immunity.
- Why that matters: controller chips are one component of an SSD module. Branded SSDs ship with vendor‑specific firmware, PCB designs, NAND choices, and power delivery arrangements. A controller vendor can reasonably say an internal test population showed no failures while certain branded SKUs in the wild — which carry manufacturer firmware tailored for module specifics — might still be exposed until each SKU is validated. This is the reason vendor advisories typically list tested firmware IDs and module SKUs rather than making blanket claims.
- The practical takeaway: Silicon Motion’s forum reply is a positive early signal for users who have Silicon Motion‑based SSDs, but it is provisional. Until Silicon Motion publishes a formal advisory (firmware IDs, tested SKUs, or an official “no affected SKUs” bulletin) the community‑sourced reassurance should be treated as informative, not dispositive.
Technical anatomy — why a Windows update can make drives “vanish”
Modern NVMe SSDs are tightly coupled embedded systems: the OS kernel and NVMe driver, PCIe transport, controller firmware, DRAM or Host Memory Buffer (HMB) usage, flash translation layers (FTL), and NAND itself all interact under high‑stress workloads. Several plausible, non‑exclusive mechanisms explain the observed failure fingerprint:- Controller firmware hang due to host timing changes. A host update that alters buffering, DMA timing, or command ordering can push certain firmware state machines into an unrecoverable lock, making the controller stop responding at the PCIe/NVMe level. When the controller fails to answer admin commands, Windows may mark the device as removed. Community tests that show unreadable SMART telemetry are consistent with this scenario.
- HMB / DRAM‑less sensitivity. DRAM‑less controllers offload part of their mapping/cache to the host via NVMe HMB. Changes in how the OS allocates, times, or synchronizes HMB regions can expose race conditions in DRAM‑less firmware. Earlier Windows 11 previews already demonstrated HMB fragility on specific models, making this vector plausible.
- Sustained sequential‑write stress. Long, continuous writes stress SLC caches, garbage collection, and metadata updates in ways that short daily desktop writes do not. Community reproductions typically used large sustained writes (often ~50 GB) against drives that were already ~50–60% full — conditions under which firmware edge cases are more likely to surface. These operational parameters are reproducible but should be treated as heuristics rather than hard thresholds.
How vendors and Microsoft have responded so far
- Microsoft: The official KB page for the August 12, 2025 cumulative update (KB5063878) lists the release and its build number and initially stated no known storage issues on the KB page, while other Microsoft channels acknowledged being “aware of” community reports and requested telemetry through Feedback Hub. Microsoft historically uses Known Issue Rollbacks (KIR) or targeted patches when OS behavior contributes; such actions remain possible here depending on telemetry findings. (support.microsoft.com)
- Phison: The controller maker has publicly acknowledged the investigation, saying it is working with Microsoft and partners to determine affected controllers and to remediate where necessary. Phison’s visibility in the incident stems from its large market share — but that ubiquity can make it appear over‑represented in raw counts even when the problem is an interaction across vendors. Phison also took action after forged internal documents were circulated, highlighting the confusion such events create. (bleepingcomputer.com)
- Silicon Motion: The forum reply attributed to Silicon Motion stating no observed SMI controller failures is a helpful data point; however, it remains a community‑sourced statement and not the same as a formal, SKU‑validated support advisory. Users should watch for an official Silicon Motion bulletin or for SSD vendors that use SMI controllers to publish SKU‑level validation.
- SSD makers: Branded SSD manufacturers are the distribution channel for firmware fixes. When a controller vendor produces a firmware patch, SSD makers must often adapt and validate that firmware for the specific module and then publish it through their dashboard utilities. That validation step is critical but time‑consuming, and it’s the reason coordinated advisories and staged rollouts tend to lag community discoveries.
Risks, caveats and unverifiable claims
- Provisional nature of early statements: Any vendor statement that is a forum reply or informal comment should be treated as provisional until accompanied by a published advisory listing specific firmware versions or SKUs. Silicon Motion’s “so far” remark falls into this category: useful, but not conclusive.
- Community lists ≠ definitive blacklists: Enthusiast labs produce helpful early model lists, but firmware revisions and module SKUs vary; the same model number can ship with different controller firmware across batches. Community lists are investigative leads, not authoritative exclusion lists. Treat them as prioritization tools for testing and backups.
- Misattribution risk: Phison’s visibility made early threads focus on Phison controllers, and that over‑indexing risk was amplified by forged materials that falsely assigned blame. Premature single‑vendor attribution can mislead remediation efforts and delay the correct cross‑stack fix.
- Numbers as heuristics: The common reproduction threshold (~50 GB of sustained writes against drives ~50–60% full) is a community‑derived heuristic, not a guaranteed trigger point. Some users will see no issues under those conditions; others will. Use heuristics for risk management, not as absolutes.
Practical, step‑by‑step guidance for users and admins
- Back up now. Prioritize irreplaceable data to an independent medium (external drive, NAS, or cloud storage) and verify the backups. Data integrity is the primary risk.
- Avoid large, continuous writes on recently updated systems. Delay mass game installs, archive extraction, disk cloning, VM image transfers, and other sustained‑write operations until vendors publish mitigations. If you must transfer large data, break it into smaller batches (ideally below the community heuristic of ~50 GB) and monitor the drive during the transfer.
- Identify your SSD controller and firmware. Use tools such as CrystalDiskInfo, HWInfo, or the SSD vendor’s dashboard (Samsung Magician, WD Dashboard, Corsair iCUE, Crucial Storage Executive) to capture controller family and firmware build. Save screenshots or logs for support cases. If your drive is Silicon Motion‑based and you saw the forum reassurance, still verify the SSD maker’s site for firmware advisories.
- If you experience a failure: stop writing to the device immediately. Collect Event Viewer logs, Device Manager and Disk Management screenshots, and any vendor utility output. Reboot only if recommended by vendor guidance; in some cases a reboot brings the drive back, in others it does not. Report the incident to Microsoft via Feedback Hub and to your SSD vendor with logs and diagnostic artifacts. Preserve forensic material if possible.
- Enterprise deployments: hold KB5063878 in broader rings until vendor and Microsoft advisories clarify affected SKUs and remediation paths. Use WSUS/Intune to control rollouts and run representative sustained‑write stress tests on sample hardware and firmware revisions. Prepare rollback plans and RMA procedures for affected endpoints.
- Firmware updates: apply firmware updates only when an SSD vendor explicitly links the firmware change to this regression and provides installation instructions. Firmware flashing carries its own risks; follow vendor guidance and ensure power stability during the update.
For Silicon Motion customers: a targeted note
If your SSD lists Silicon Motion or SMI in the controller field, the forum reply relayed by community outlets is positive but not binding. Check your SSD vendor’s support portal and dashboard utility for SKU‑level advisories. If no advisory exists and you rely on that drive for important data, maintain verified backups and avoid large, continuous writes until either:- Silicon Motion publishes a formal “no affected SKUs” advisory, or
- Your SSD vendor confirms the drive and firmware build are validated as safe, or
- Microsoft and the controller ecosystem publish a coordinated remediation.
What to watch next — signals that matter
- Official vendor advisories listing confirmed affected firmware IDs and supported SKUs (the strongest clearing evidence is a vendor‑published matrix saying “no affected SKUs” or listing exact firmware versions that are safe).
- Vendor firmware downloads and release notes that explicitly reference the regression or include fixes for the symptom profile. SSD manufacturers are the delivery path for controller‑level updates.
- Microsoft adding a Known Issue entry to the KB or issuing a Known Issue Rollback (KIR) or targeted host mitigation if the root cause is demonstrably host‑side; that would be the clearest signal that Microsoft considers host behavior a contributing factor. (support.microsoft.com)
- Diverse independent test benches reproducing (or failing to reproduce) the issue on a broad matrix of controllers, firmware, fill levels, and sustained‑write profiles; repeatable reproduction across labs increases confidence in root‑cause hypotheses.
Critical analysis — strengths and systemic weaknesses revealed
Strengths:- Rapid community triage and reproducible tests transformed scattershot complaints into a credible cross‑stack investigation within days. Enthusiast labs and specialist outlets played a decisive early role.
- Vendor engagement (Phison’s public acknowledgement, Microsoft collecting telemetry) shows the ecosystem can mobilize quickly when reproducible failure fingerprints emerge. (bleepingcomputer.com)
- Fragmentation of SKUs and firmware slows remediation. Controller vendors, SSD makers, and system integrators must validate fixes per module SKU — a correct but time‑consuming process that prolongs exposure windows.
- Informal communications (forum replies, community threads) can reassure but also create false confidence if not followed by SKU‑level advisories. Silicon Motion’s forum reply illustrates this tension: good news, but not the same as a published, auditable validation.
- Information noise and forged documents (notably the falsified advisory that misattributed blame) increase confusion and can misdirect responses. Accurate, verified vendor communication during incidents is essential to avoid unnecessary panic and misapplied mitigations.
Bottom line
Silicon Motion’s early, forum‑relayed statement that “none of our controllers are affected” is encouraging for owners of SMI‑based drives, but it is a provisional observation rather than a formal, SKU‑validated clearance. The incident surrounding KB5063878 (and related preview patches) is an active cross‑stack investigation with reproducible failure fingerprints under sustained writes; Phison has acknowledged an investigation and Microsoft is collecting telemetry and engaging partners. Until vendors publish SKU‑level advisories or Microsoft issues a targeted correction, the defensible approach remains unchanged: back up urgently, avoid heavy sequential writes on systems that received KB5063878/K5062660, identify your SSD controller and firmware, and apply only vendor‑recommended firmware updates that explicitly address this regression.Users and administrators should monitor official vendor support pages and the Windows update health channels for formal advisories and firmware downloads. Treat community reassurances as useful lead indicators, not as substitutes for vendor‑validated confirmation.
Conclusion: Silicon Motion's message provides a welcome early signal, but it does not close the case. Robust backups and measured, evidence‑based patch management remain the best protection while the industry works through cross‑stack telemetry and publishes definitive firmware and OS mitigations.
Source: Club386 Silicon Motion says none of its SSD controllers are affected by the Windows 11 death bug, so far | Club386
