Tape Backup Script Documentation

Overview

This script facilitates backups to a tape device. It supports full backups, incremental backups, and dry-run operations for testing without writing to the tape. Logs and snapshots are maintained to track operations and incremental backups.

Usage

tape_backup.sh <folder_to_backup> <mode> [tape_device]

Parameters

• <folder_to_backup>: Mandatory. The folder to back up.
• <mode>: Mandatory. Specifies the type of backup:
  • full: Perform a full backup.
  • inc: Perform an incremental backup (uses snapshots).
  • dry: Perform a dry run (testing without writing to the tape).
• [tape_device]: Optional. The tape device to use. Defaults to /dev/st0.

Examples

• Full backup:

  tape_backup.sh /path/to/folder full

• Incremental backup to a specific tape device:

  tape_backup.sh /path/to/folder inc /dev/nst0

• Dry run:

  tape_backup.sh /path/to/folder dry

Script Details

Directory Setup

• Logs: Stored in tape_backup_logs within the script's directory.
• Snapshots: Stored in tape_backup_snapshots within the script's directory.

Key Variables

• DEFAULT_TAPE_DEVICE: Default tape device (/dev/st0).
• SCRIPT_DIR: Directory of the script.
• LOG_DIR: Directory for log files.
• SNAPSHOT_DIR: Directory for snapshot files.
• DATE: Current date and time for unique log file naming.

Functional Description

1. Argument Validation:

   • Ensures the required folder exists and validates the mode parameter.
   • Provides usage instructions if parameters are missing or invalid.

2. Mode-Based Operations:

   • Full Backup (full):
     • Backs up the specified folder to the tape device.
     • Removes any existing snapshot file.
   • Incremental Backup (inc):
     • Performs a backup that only includes changes since the last backup using a snapshot file.
   • Dry Run (dry):
     • Simulates a backup without writing to the tape, using /dev/null.

3. Error Handling:

   • Logs errors and exits with a failure status if any issues occur during execution.

4. Logging:

   • All operations are logged in tape_backup_logs/backup_<date>.log.

Exit Status

• 0: Success.
• 1: Failure due to invalid arguments or backup errors.

Files and Directories

• Log Directory: tape_backup_logs
• Snapshot Directory: tape_backup_snapshots
• Log File: backup_<date>.log (e.g., backup_2025-01-22_16-30-45.log)
• Snapshot File: <folder_name>_snapshot.snar

Notes

• Incremental backups require a snapshot file to track changes. This file is automatically managed by the script.
• Ensure the specified tape device is correctly connected and configured before running the script.

Troubleshooting

• Backup Failed:
  • Check the log file for detailed error messages.
  • Verify the tape device is operational and accessible.
• Invalid Folder:
  • Confirm the folder path exists and is accessible.

Author

Jaronchai Dilokkalayakul 2025 Tohoku University, Information Biology Lab