What does HRESULT 0xC0380054 (ERROR_VOLMGR_NUMBER_OF_DISKS_IN_PLEX_INVALID) mean?

ERROR_VOLMGR_NUMBER_OF_DISKS_IN_PLEX_INVALID

Read the code at the owning storage layer: volmgr number of disks in plex invalid

ERROR_VOLMGR_NUMBER_OF_DISKS_IN_PLEX_INVALID has unsigned value 0xC0380054. In the volmgr layer, the operation is rejected because the plex disk count is incompatible with the chosen simple, striped, mirrored or parity organization. Diagnosis should follow volume plex descriptor, layout type and regeneration state through one controlled state transition.

Keep the first result attached to its request parameters and object instance. Cleanup failures or a later drive-letter change are secondary evidence, not replacements for the original failure.

Build a trustworthy incident record

Do not overwrite this result with a close, detach or rollback error. Preserve the causal order so the original storage contract remains visible.

Controlled comparison

1. Before changing state, freeze the failing generation and save volume ID, plex ordinal, plex type, member array, active/inactive state, health status and current regeneration job.
2. Exercise this exact comparison: 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.
3. During the comparison, keep image bytes, unrelated disks, provider policy and cluster topology fixed.
4. After the test, record the next return value and the durable object state; crossing the boundary should expose a later result rather than silently retrying.

Use ERROR_VOLMGR_UNEXPECTED_DISK_LAYOUT_CHANGE as the nearest comparison. It is specific to the plex disk count is incompatible with the chosen simple, striped, mirrored or parity organization; the neighboring result belongs to another validation or lifecycle branch. Keeping both names prevents a generic storage label from hiding the actual owner.

Mechanism-specific note

The count field is part of the layout contract rather than an advisory value. 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. Apply the change through the supported storage API, then close and reacquire affected objects before retrying.

• 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 condition.
• the nearby ERROR_VOLMGR_UNEXPECTED_DISK_LAYOUT_CHANGE path remains separately testable and separately logged.

Technical references

• Microsoft: COM error codes for VOLMGR, VHD and SDIAG — documents the supported management path relevant to this HRESULT.
• Microsoft: Virtual Disk Service object model — defines the volmgr objects used to interpret it.
• Microsoft: Pack object — primary API or object-model reference.
• Microsoft: Virtual Disk Service common return codes — use this source to verify volmgr state and parameters.