What does HRESULT 0xC05CFF02 (ERROR_SVHDX_UNIT_ATTENTION_CAPACITY_DATA_CHANGED) mean?

ERROR_SVHDX_UNIT_ATTENTION_CAPACITY_DATA_CHANGED

What ERROR_SVHDX_UNIT_ATTENTION_CAPACITY_DATA_CHANGED means

ERROR_SVHDX_UNIT_ATTENTION_CAPACITY_DATA_CHANGED (0xC05CFF02) reports a SCSI Unit Attention condition for a shared virtual disk because the device capacity visible to the initiator changed.

Operational meaning

Unit Attention is a notification that device state changed. The important change is capacity. The initiator should refresh capacity and any dependent geometry before continuing I/O; the HRESULT by itself does not prove that the VHDX is corrupt.

Evidence to preserve

• Record the shared VHDX/VHD identity, disk path, node or initiator, and the first operation that observed 0xC05CFF02.
• Capture the reported capacity before and after the event together with the SCSI Unit Attention information.
• Correlate Hyper-V and Failover Clustering events across nodes when the disk is shared by a guest cluster.
• Keep protocol/version and reservation state when they are relevant to the shared-disk path.

Recovery and verification

Refresh the device capacity and reconcile shared-disk state before retrying I/O that depends on the old geometry. A successful verification should show that every participating node observes the same intended capacity and that the original operation proceeds without another unexplained capacity-change notification.

Official references

• Microsoft: HRESULT values
• Microsoft: Structure of COM error codes