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ERROR_FILEMARK_DETECTED
a tape access reached a filemark.
ERROR_FILEMARK_DETECTED means that a sequential-media read or positioning operation encountered a logical file boundary recorded on tape. In this case, the decisive context is tape backup sets containing multiple logical files, together with current tape file/block position and requested movement.
Where the result appears
- tape backup sets containing multiple logical files.
- restore tools scanning records or volumes.
- archive verification and tape-copy utilities.
- drive commands that position relative to filemarks.
Typical causes
- the reader reached the intended end of a logical tape file.
- the caller expected more data before the boundary.
- positioning count or initial tape location was wrong.
- backup metadata and physical filemark layout disagree.
Evidence to collect
- current tape file/block position and requested movement.
- backup-set catalog entry and expected filemark sequence.
- bytes returned before the mark and drive status.
- whether the operation treats filemarks as normal boundaries or exceptional conditions.
For this condition, begin the investigation with current tape file/block position and requested movement. Correlate it with backup-set catalog entry and expected filemark sequence and check whether the reader reached the intended end of a logical tape file. Capture the original this result immediately after the failing call so later cleanup does not replace the thread-local error value.
Handling and recovery
Interpret the filemark according to the archive format. It may be a normal delimiter requiring the next logical file, not a failure requiring media replacement. If encountered unexpectedly, stop and reconcile catalog metadata with actual tape position before continuing.
Any retry policy for it should be tied to evidence that the caller expected more data before the boundary has changed. Before another attempt, verify bytes returned before the mark and drive status. If backup metadata and physical filemark layout disagree still applies, stop the retry sequence and preserve the first diagnostic event.
Common misinterpretation
A filemark is not the physical end of the cartridge and does not by itself imply unreadable media.
Guidance for developers
When surfacing this result through another layer, retain its Win32 domain, numeric value, and the operation described by restore tools scanning records or volumes. A useful telemetry record also includes whether the operation treats filemarks as normal boundaries or exceptional conditions. For a-related handling, decisions must use the numeric value and documented API contract rather than localized wording.
A focused test should reproduce the condition in which positioning count or initial tape location was wrong, assert this result, and confirm that the program releases resources associated with archive verification and tape-copy utilities. The recovery test should also verify that current tape file/block position and requested movement is refreshed before the operation resumes.
References
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