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ERROR_VIRTDISK_DISK_ONLINE_AND_WRITABLE
Why this is narrower than a generic disk error: virtdisk disk online and writable
Windows returns ERROR_VIRTDISK_DISK_ONLINE_AND_WRITABLE, value 0xC03A001F, at the virtdisk boundary. It means that the physical disk is online with write access when the operation requires it to be offline or read-only for it. Preserve the exact handle and generation of Virtual Disk API provider, image format and host-disk state before any rescan changes the evidence.
The Virtual Disk API chooses a format provider from VIRTUAL_STORAGE_TYPE, opens an image with explicit access rights and can attach it as a disk for it. Provider selection, backing-chain integrity, host-file attributes, sector geometry and operating-system ownership are independent validation stages for it. This object model determines which identifiers, counts and ownership state are meaningful.
The standard message identifies the immediate condition, but this result also requires the producer API, object topology and attempted state transition. Capture them before an automatic refresh advances the storage generation.
Storage facts that change the diagnosis
| Storage diagnostic field | Value |
|---|---|
| Closest comparison | ERROR_VIRTDISK_DISK_ALREADY_OWNED |
| Owning object | Virtual Disk API provider, image format and host-disk state |
| Rejected invariant | the physical disk is online with write access when the operation requires it to be offline or read-only |
| Identity and generation | image path, VIRTUAL_STORAGE_TYPE, provider/vendor IDs, VHD/VHDX/VHD Set identifiers, host sector sizes, attach flags, ownership and online/read-only state |
| Narrow experiment | record the current owner and disk attributes, release or offline the disk in a test scope, and retry without changing the image |
When it is followed by a secondary cleanup failure, store both codes with timestamps and retain this one as the initiating result.
A/B test for this HRESULT
- serialize the failing request and the enumeration from which its identifiers came.
- Preserve image path, VIRTUAL_STORAGE_TYPE, provider/vendor IDs, VHD/VHDX/VHD Set identifiers, host sector sizes, attach flags, ownership and online/read-only state while every handle is still valid.
- Repeat the operation using this controlled change: record the current owner and disk attributes, release or offline the disk in a test scope, and retry without changing the image.
- Close and reacquire the relevant objects, then run once more to test lifecycle correctness after this result.
Compare traces for ERROR_VIRTDISK_DISK_ALREADY_OWNED and this result. The latter page covers a nearby storage boundary, whereas it rejects the physical disk is online with write access when the operation requires it to be offline or read-only. A correct caller should be able to reproduce each case independently.
Mechanism-specific note
The physical disk attributes are incompatible with an operation that needs exclusive offline or read-only access. Capture disk number, unique ID and current attributes while diagnosing this result. Offline the correct disk only after proving it is not serving a mounted volume, cluster resource or another virtual machine.
Corrective action and regression check
Correct the provider, image format, backing-file chain, host geometry or disk ownership identified by the failing call, then reopen the image to obtain a new handle before retrying while diagnosing it. Apply the change through the supported storage API, then close and reacquire affected objects before retrying.
- The original request now reaches success or a documented later status with the intended layout and access mode for it.
- A new enumeration reports internally consistent IDs, counts, geometry and ownership for the object corrected after it.
- The passing state survives the lifecycle transition relevant to it, such as reopen, remount, owner change or detach/attach.
- The application still distinguishes it from
ERROR_VIRTDISK_DISK_ALREADY_OWNEDand has no unbounded retry loop.
Do not use it as a reason to edit dynamic-disk sectors, VHDX metadata, RCT sidecars or snapshot support files directly. Unsupported edits can turn a recoverable state mismatch into persistent corruption.
Technical references
- Microsoft: Virtual Disk API — primary API or object-model reference for the boundary.
- Microsoft: OpenVirtualDisk — use this source to verify virtdisk state and parameters for it.
- Microsoft: AttachVirtualDisk — documents the supported management path relevant to it.
- Microsoft: GetVirtualDiskInformation — defines the virtdisk objects used to interpret it.
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