Offline Media

License: PRO+ (Professional Edition or higher)
Module Type: Alternate Scanner
Author: Diskover Data, Inc.

Overview / Use Cases

The Offline Media Scanner lets you build a persistent, searchable catalog of removable and offline storage — tapes, external drives, removable disks — without needing every volume physically mounted at the same time. Each media volume is scanned and indexed under a virtual root directory, so your team can search across hundreds or thousands of offline volumes right from the Diskover Web UI.

Think of it as a card catalog for your physical media library. Mount a tape, scan it, swap in the next one, scan again. Diskover stitches together a unified view of everything under a single virtual path like /OFFLINE_MEDIA, with each volume neatly filed under its own label.

Who Benefits and How

• Media & Entertainment Archivists — Search across thousands of archived tapes to locate project files, raw footage, or audio assets without pulling tapes from the vault. The virtual path tells you exactly which tape to retrieve.

• IT Administrators & Backup Operators — Catalog collections of external USB or eSATA backup drives by serial number or asset tag. Quickly answer questions like "which drive has last quarter's database exports?" without plugging in every drive.

• Compliance & Disaster Recovery Teams — Verify that critical files exist somewhere in your offline archive set. Run gap analysis across all backup volumes from a single search, supporting audit readiness and recovery planning.

Requirements

System Requirements

Python Dependencies

All required packages are included with the standard Diskover installation. No additional Python dependencies are needed.

Installation

Step 1: Install Scanner Package

Linux:

dnf install diskover-scanner-offline_media

Windows:

The scanner files are included with the Diskover Windows installation. No separate installation step is required.

Install locations:

• Linux: /opt/diskover/scanners/scandir_offline_media/

• Windows: C:\Program Files\Diskover\scanners\scandir_offline_media\

Step 2: Create Cache Directory

The scanner stores directory listing data in a SQLite cache database. You need to create the cache directory before the first scan.

Linux:

sudo mkdir -p /opt/diskover/__dircache_offline_media__
sudo chown diskover:diskover /opt/diskover/__dircache_offline_media__
sudo chmod 750 /opt/diskover/__dircache_offline_media__

Windows (Command Prompt as Administrator):

mkdir "C:\Program Files\Diskover\__dircache_offline_media__"

Step 3: Verify Installation

Confirm the scanner module loads correctly:

Linux:

cd /opt/diskover
python3 -c "from scanners.scandir_offline_media import scandir_offline_media; print('Scanner module loaded successfully')"

Windows:

cd "C:\Program Files\Diskover"
python -c "from scanners.scandir_offline_media import scandir_offline_media; print('Scanner module loaded successfully')"

Step 4: Perform a Test Scan

Run a quick test scan on a mounted media volume to confirm everything works end-to-end:

Linux:

cd /opt/diskover
export MEDIA_LABEL=TEST_MEDIA_001
python3 diskover.py -i diskover-offline-test --altscanner scandir_offline_media /mnt/test_media

Windows:

cd "C:\Program Files\Diskover"
set MEDIA_LABEL=TEST_MEDIA_001
python diskover.py -i diskover-offline-test --altscanner scandir_offline_media E:\

If the scan completes without errors and you can see results in Diskover's search UI, the installation is working correctly.

Configuration

Configuration is managed through the Diskover Admin UI under Settings > Alternate Scanners > Offline Media.

Configuration Parameters

Environment Variable Requirements

The scanner requires one mandatory environment variable set before each scan:

Environment Variable Overrides

You can override certain configuration parameters at runtime using environment variables:

Configuration via Diskover Admin

1. Navigate to Settings > Alternate Scanners > Offline Media

2. Adjust the settings as needed:

   • Verbose — Enable for troubleshooting cache behavior

   • Root Path — Set the virtual root directory (default /OFFLINE_MEDIA)

   • Cache Directory — Specify a custom cache location if needed

   • Directory List Expire — Set expiration time in seconds (0 for never)

   • Load DB Memory — Enable for performance (use with caution)

3. Save the configuration

Sample Configuraiton in Diskover Admin:

Here is the beginning of our sample configuration There are many other configuraitons for the Offline Media Scanner - covered in detail below!

Configuration Examples

Tape Archive with Custom Root Path

If you want your tape library to appear under a different virtual root than the default:

verbose: false
root_path: /TAPE_ARCHIVE
cachedir: /opt/diskover/__dircache_offline_media__/
dirlist_expire: 0
load_db_mem: false

High-Performance External Drive Indexing

For scenarios where you're rapidly indexing many drives and want maximum speed (with the understanding that a crash could corrupt the cache):

verbose: false
root_path: /OFFLINE_MEDIA
cachedir: /opt/diskover/__dircache_offline_media__/
dirlist_expire: 3600
load_db_mem: true

Virtual Path Structure

The scanner creates a virtual directory hierarchy that organizes all your offline media under one roof:

/OFFLINE_MEDIA/                         ← root_path (configurable)
├── TAPE_001/                           ← MEDIA_LABEL from first scan
│   ├── projects/
│   │   ├── project_a/
│   │   └── project_b/
│   └── archive/
├── TAPE_002/                           ← MEDIA_LABEL from second scan
│   └── data/
└── EXTERNAL_DRIVE_SN12345/             ← MEDIA_LABEL from third scan
    └── backups/

Physical paths are transformed automatically. For example:

• Physical: /mnt/tape/projects/project_a/file.txt

• Virtual: /OFFLINE_MEDIA/TAPE_001/projects/project_a/file.txt

This means users searching in Diskover see the virtual path, which tells them both the file location within the volume and which media volume (TAPE_001) contains it.

Usage / Execution

The Offline Media Scanner is a standard alternate scanner that integrates with diskover.py via the --altscanner flag.

Setting the Media Label

Before every scan, set the MEDIA_LABEL environment variable to uniquely identify the volume:

Linux/macOS:

export MEDIA_LABEL=YOUR_MEDIA_IDENTIFIER

Windows (Command Prompt):

set MEDIA_LABEL=YOUR_MEDIA_IDENTIFIER

Windows (PowerShell):

$env:MEDIA_LABEL = "YOUR_MEDIA_IDENTIFIER"

First Scan — Creating a New Index

When scanning your first media volume, create a new index:

Linux:

cd /opt/diskover
export MEDIA_LABEL=TAPE_2024_0001
python3 diskover.py -i diskover-offline-media --altscanner scandir_offline_media /mnt/tape

Windows:

cd "C:\Program Files\Diskover"
set MEDIA_LABEL=TAPE_2024_0001
python diskover.py -i diskover-offline-media --altscanner scandir_offline_media E:\

Subsequent Scans — Appending to an Existing Index

This is critical: When adding more media volumes to an existing index, you must use the -a (add to index) flag. Without -a, Diskover will overwrite the existing index and you'll lose all previously indexed media.

Swap your media, set a new label, and run with -a:

Linux:

cd /opt/diskover
export MEDIA_LABEL=TAPE_2024_0002
python3 diskover.py -i diskover-offline-media -a --altscanner scandir_offline_media /mnt/tape

Windows:

cd "C:\Program Files\Diskover"
set MEDIA_LABEL=TAPE_2024_0002
python diskover.py -i diskover-offline-media -a --altscanner scandir_offline_media E:\

Repeat this process for each additional volume — mount, set label, scan with -a.

Path Format Reference

Advanced Usage Examples

Custom Index Name:

export MEDIA_LABEL=ARCHIVE_VOL_42
python3 diskover.py -i diskover-tape-library-2024 --altscanner scandir_offline_media /mnt/tape

Verbose/Debug Logging:

export MEDIA_LABEL=DEBUG_TAPE_001
python3 diskover.py -i diskover-offline-test --altscanner scandir_offline_media --loglevel DEBUG /mnt/tape

Custom Virtual Root Path at Runtime:

export diskover_offlinemedia_root_path="/TAPE_ARCHIVE"
export MEDIA_LABEL=TAPE_001
python3 diskover.py -i diskover-tapes --altscanner scandir_offline_media /mnt/tape

Inline Environment Variable (Linux — useful for cron jobs):

MEDIA_LABEL=TAPE_001 python3 /opt/diskover/diskover.py -i diskover-offline-media --altscanner scandir_offline_media /mnt/tape

Integration with Index Tasks

When configuring Offline Media scans through Diskover's Index Task system:

Note: When using Index Tasks, you still need to ensure the MEDIA_LABEL environment variable is set in the execution environment before the task runs. For automated workflows, consider setting this in the task runner's environment or in a wrapper script.

Performance Tips

• Leave load_db_mem as false unless you're sure your scans won't be interrupted. The performance gain is modest for most workloads, and a crash with this enabled can corrupt the cache database.

• The cache is most helpful for re-scanning the same volume. For one-time scans of media you won't re-scan, the cache still works but provides less benefit.

• Use dirlist_expire: 0 (the default) for offline media, since the content of archived volumes typically doesn't change between scans.

• Choose meaningful, unique media labels — tape barcodes and drive serial numbers work well. Duplicate labels will cause confusing overlapping data in the index.

Troubleshooting

Common Issues

Debug Logging

Enable detailed logging to diagnose issues:

python3 /opt/diskover/diskover.py --altscanner scandir_offline_media --loglevel DEBUG /mnt/tape

To specifically monitor cache behavior, enable the verbose configuration parameter, which logs cache hits and misses to the diskover.scandir_dircache logger.

Log File Locations

• Linux: /var/log/diskover/diskover.log

• Windows: Check Diskover service logs or the configured log output location.

Common Error Messages

ConfigurationError: The "MEDIA_LABEL" environment variable is not set!

This means the scanner could not find the MEDIA_LABEL in the current environment. This is especially common when running scans from cron, systemd, or other automated schedulers that don't inherit your shell's environment variables.

Resolution: Set the variable inline with the command:

# Cron example
0 2 * * * MEDIA_LABEL=TAPE_001 cd /opt/diskover && python3 diskover.py -i diskover-offline -a --altscanner scandir_offline_media /mnt/tape

Error creating dir cache directory

The scanner cannot create or access the cache directory.

Resolution: Verify the cache directory exists and has correct ownership and permissions:

ls -la /opt/diskover/__dircache_offline_media__
# Should be owned by the diskover user with 750 permissions

SQLite database corruption warnings

If load_db_mem was enabled and a scan was interrupted, the cache database may be corrupt.

Resolution: Delete the cache database files in the cache directory and re-scan. The cache will be rebuilt automatically:

rm -f /opt/diskover/__dircache_offline_media__/*

Support

• Diskover Documentation

• Diskover Support Portal

Last Updated: April 2026