Handling ZFS Missing Parent Dinodes

Bacula Enterprise Only

This solution is only available for Bacula Enterprise. For subscription inquiries, please reach out to sales@baculasystems.com.

When hard links are created across multiple directories, removing the last hard link created can result in missing parent dinodes for the remaining links. Any subsequent modifications to those files will not be detected by zfs diff. The BSnapDiff Plugin for ZFS identifies and corrects these errors.

During any backup operation, Bacula may detect files that are missing their internal parent directory status. When found, the Bacula File Daemon repairs the parent directory status by temporarily creating and then removing a hard link to the file on the live file system (not the snapshot). Although this behavior is unusual for a backup process, it is required to ensure that future changes to the file are properly recognized by zfs diff.

A summary of repaired files, if any, is reported in the backup log:

zdb_fix_missing_dinodes bsnapdiff relinked 16 files

This behavior is specific to the ZFS file system.