Generating guaranteed retention lock audit reports for cascaded replication in a deduplication backup system

A computer-implemented method to create reports of retention locked files in a backup system having a plurality of storage targets storing backup copies for cascaded replication, comprising:

• creating, upon deployment of a backup server in the backup system, a hidden directory structure in local storage of a backup server filesystem;
• configuring a log rotation policy defining a period of saving retention lock settings for locked files and a report protection duration, wherein each locked file of the locked files is locked through a file retention lock process that locks a file against modification or deletion to prevent unwanted changes to the file;
• accessing the storage targets, wherein a first storage device stores a first copy of the file, a second storage device stores a replicated copy of the first copy, and one or more subsequent storage devices stores respective replicated copies of a previous replicated copy;
• writing, upon retention locking of the file, details of the file and its retention lock setting to a rotating retention lock audit (RLA) log file associated with a timestamp indicating a time of locking of the file;
• storing the RLA log file in the hidden directory structure of the filesystem;
• rotating the RLA log file upon writing a next retention locked file for storage in the hidden directory structure, as per the configured log rotation policy;
• renaming, upon the rotating, a previous version of the RLA log file in the hidden directory structure with a timestamp of a most previous locked file, wherein the previous version of the RLA log file includes retention lock settings for previously existing files generated by previous backup jobs to save past retention lock setting information of the backup system;
• replicating lock attributes and state changes to each of the first, second and respective replicated copies and to each of the first, second, and one or more subsequent storage devices;
• generating corresponding entries to the RLA log file for the lock attributes and state changes for the respective replicated copies;
• automatically generating the RLA log file upon replication at each of the first, second, and one or more subsequent storage devices.