CONTAP-56068: Nvlog replay of punch hole message might cause storage system disruption
Issue
- In some virtualization cases, the punch hole message is used to write special zero pattern blocks into the file. Using this mechanism depends on a volume-level flag being set.
- Once the message execution completes, it is nvlogged. This is done to preserve the state until the consistency point (CP) writes the content to the disk.
- If the system unexpectedly shuts down before CP completes, a replay of nvlogged messages will occur.
- Due to an issue in ONTAP, during the nvlog replay, the volume-level flag to support this mechanism might not be set. This results in punch hole messages being disallowed, leading to a disruption during NVLog replay.
- This issue exists in ONTAP 9.3 and higher.