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ERROR_VOLMGR_NUMBER_OF_DISKS_INVALID
Read the code at the owning storage layer: volmgr number of disks invalid
Windows returns ERROR_VOLMGR_NUMBER_OF_DISKS_INVALID, value 0xC038005A, at the volmgr boundary. It means that the overall disk count is inconsistent with the pack or volume layout being submitted. 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. Indices and counts are relative to the submitted layout generation, while configuration logs are replicated across participating dynamic disks while diagnosing this result. This object model determines which identifiers, counts and ownership state are meaningful while diagnosing it.
A useful record contains more than the final UI symptom: retain the first failing call, target identity, topology and state transition before management software rescans the disks while diagnosing this result.
Build a trustworthy incident record
| Storage diagnostic field | Value |
|---|---|
| Rejected invariant | the overall disk count is inconsistent with the pack or volume layout being submitted |
| 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 | serialize the exact VM_VOLUME_LAYOUT buffer, validate every count and Size field, and compare it with a layout produced by a known-good management API |
| Closest comparison | ERROR_VOLMGR_UNEXPECTED_DISK_LAYOUT_CHANGE |
| Owning object | logical volume geometry and the disk extents that realize it |
Keep this HRESULT as the primary result if rollback or cleanup reports another code; those later values describe recovery, not the first rejected invariant.
Controlled comparison
- Create a nonproduction case for it that preserves the same geometry and ownership model.
- Collect volume ID, requested length, sector sizes, extent table, plex/member counts, disk health and the exact VM_VOLUME_LAYOUT buffer before invoking the first mutating API.
- Change one condition only: serialize the exact VM_VOLUME_LAYOUT buffer, validate every count and Size field, and compare it with a layout produced by a known-good management API.
- Re-enumerate after the transition and confirm this result is not reproduced by a stale handle from the old generation.
A useful diagnostic fork is ERROR_VOLMGR_UNEXPECTED_DISK_LAYOUT_CHANGE versus this result. This code concerns the overall disk count is inconsistent with the pack or volume layout being submitted; the alternate code should remain observable after the fix, proving the application did not suppress the entire subsystem.
Mechanism-specific note
The count field is part of the layout contract rather than an advisory value while diagnosing it. Verify it against the number of serialized descriptors and against the minimum geometry required by the selected layout type. Check multiplication and addition for overflow before allocating or copying the variable-length buffer, because a correctly sized allocation can still contain a logically impossible count.
Completion criteria
Rebuild the layout from enumerated objects and checked arithmetic rather than patching one serialized field; validate counts, indices, sizes, alignment and overflow before submission while diagnosing it. Keep the correction scoped to the owning object and avoid rewriting adjacent metadata merely to make the call return success while diagnosing it.
- 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.
Before responding to it with destructive cleanup, prove which object owns the failure. Changing every disk or provider at once prevents a meaningful regression test while diagnosing it.
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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