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ERROR_VOLMGR_DIFFERENT_SECTOR_SIZE
Read the code at the owning storage layer: volmgr different sector size
Windows returns ERROR_VOLMGR_DIFFERENT_SECTOR_SIZE, value 0xC038004E, at the volmgr boundary. It means that the candidate disks expose different logical sector sizes and cannot share the requested volume geometry. Preserve the exact handle and generation of logical volume geometry and the disk extents that realize it before any rescan changes the evidence.
Dynamic volumes are represented as packs containing disks and volumes; each volume has one or more plexes, and each plex is assembled from members and extents for it. Indices and counts are relative to the submitted layout generation, while configuration logs are replicated across participating dynamic disks. This object model determines which identifiers, counts and ownership state are meaningful for it.
Keep the first result attached to its request parameters and object generation for it. Cleanup failures or a later drive-letter change are secondary evidence, not replacements for the original boundary.
Build a trustworthy incident record
| Storage diagnostic field | Value |
|---|---|
| Closest comparison | ERROR_VOLMGR_UNEXPECTED_DISK_LAYOUT_CHANGE |
| Owning object | logical volume geometry and the disk extents that realize it |
| Rejected invariant | the candidate disks expose different logical sector sizes and cannot share the requested volume geometry |
| Identity and generation | volume ID, requested length, sector sizes, extent table, plex/member counts, disk health and the exact VM_VOLUME_LAYOUT buffer |
| Narrow experiment | compare a disk set with identical logical sector sizes against one mixed-geometry test set while keeping extent counts unchanged |
Do not overwrite this result with a close, detach or rollback error. Preserve the causal order so the original storage contract remains visible while diagnosing it.
Controlled comparison
- serialize the failing request and the enumeration from which its identifiers came for it.
- Preserve volume ID, requested length, sector sizes, extent table, plex/member counts, disk health and the exact VM_VOLUME_LAYOUT buffer while every handle is still valid.
- Repeat the operation using this controlled change: compare a disk set with identical logical sector sizes against one mixed-geometry test set while keeping extent counts unchanged.
- Close and reacquire the relevant objects, then run once more to test lifecycle correctness after this result.
Use ERROR_VOLMGR_UNEXPECTED_DISK_LAYOUT_CHANGE as the nearest comparison. This result is specific to the candidate disks expose different logical sector sizes and cannot share the requested volume geometry; the neighboring result belongs to another validation or lifecycle branch. Keeping both names prevents a generic storage label from hiding the actual owner while diagnosing it.
Mechanism-specific note
Record logical and physical sector sizes for every layer: image format, host file system and physical disk. Alignment must be checked with integer arithmetic before truncation. Copying an image to a different device can change the host geometry even when the image bytes and virtual capacity remain identical.
Completion criteria
Refresh the disk layout, serialize the change as one volume-manager transaction and reject any external partition mutation until commit or rollback completes. Keep the correction scoped to the owning object and avoid rewriting adjacent metadata merely to make the call return success while diagnosing this result.
- the first retry uses newly enumerated identifiers rather than cached handles.
- The durable metadata or provider state agrees with the success returned after it.
- A second run after close/reopen does not recreate the rejected the condition.
- the nearby
ERROR_VOLMGR_UNEXPECTED_DISK_LAYOUT_CHANGEpath remains separately testable and separately logged.
A reboot, blanket disk conversion or deletion of storage metadata is not a justified first response to it; it changes multiple invariants and can erase the evidence needed to identify the defect.
Technical references
- Microsoft: COM error codes for VOLMGR, VHD and SDIAG — primary API or object-model reference for the boundary.
- Microsoft: Virtual Disk Service object model — use this source to verify volmgr state and parameters for it.
- Microsoft: Pack object — documents the supported management path relevant to it.
- Microsoft: Virtual Disk Service common return codes — defines the volmgr objects used to interpret it.
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