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ERROR_SVHDX_UNIT_ATTENTION_RESERVATIONS_PREEMPTED
Reservation ownership was displaced
ERROR_SVHDX_UNIT_ATTENTION_RESERVATIONS_PREEMPTED means that a prior operation caused this initiator’s persistent reservation to be preempted. In SCSI Persistent Reservations, registration and reservation are separate concepts: multiple initiators can register keys, while the reservation establishes access rights for the logical unit. Preemption is therefore a cluster-coordination event, not an ordinary access-control denial.
In a healthy failover design, preemption can be deliberate. A surviving owner may fence a failed member so that an old or partitioned node cannot continue writing shared storage. In an unexpected case, the same status can expose split-brain risk, a stale guest, an incorrect reservation key, an unintended management action, or incorrect recovery sequencing.
Required checks
- Identify which component issued the preempt action and whether it was part of a planned failover, fencing operation, or cluster recovery.
- Read the current Persistent Reservation state instead of assuming that the former holder may resume I/O. Inspect registrations, reservation holder, reservation type, and generation.
- Check the cluster quorum and resource-owner history before attempting to register or reserve again.
- Keep the affected initiator from writing the shared disk until the cluster’s ownership rules have selected the valid owner. A manual reclaim can turn a protection event into corruption.
Difference from related statuses
A preempted reservation concerns the access grant itself. ERROR_SVHDX_UNIT_ATTENTION_REGISTRATIONS_PREEMPTED is about registration membership, while ERROR_SVHDX_RESERVATION_CONFLICT is the command result returned when the current initiator lacks the required reservation rights. Those states should not be collapsed into one generic “disk busy” diagnosis.
References
- Linux kernel documentation: persistent reservations and fencing
- sg3_utils: PRIN and PROUT operations
- Microsoft Open Specifications: Remote Shared Virtual Disk Protocol
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