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Managing Tape Archives with git-annex: A Special Remote for Sequential Media

Talk Steffen Vogel Distribits 2025 HdU plenary hall Hardware Preservation Tool Git-Annex

Use git-annex to manage your tape archive index.

Magnetic tape remains a highly reliable and cost-effective medium for long-term data storage. However, its sequential nature and limited integration with modern software workflows often hinder adoption outside traditional enterprise environments. This talk introduces a new approach that integrates tape storage with git-annex through a purpose-built special remote called git-annex-remote-tape, enabling, versioned data management on offline, high-capacity media.

We begin with a brief technical overview of the LTO ecosystem, focusing on tape operation via SCSI command sets and connectivity through SAS or Fibre Channel interfaces. These drives are well-supported in Linux via device nodes (e.g., /dev/st0) and managed with tools such as mt, tar, and sg3_utils. Despite robust hardware capabilities — such as hardware encryption and streaming compression — integrating tape into file-level workflows remains challenging, especially for applications requiring metadata versioning and content addressing.

To address this gap, we introduce git-annex-remote-tape, a special remote that treats tape as a managed backend for git-annex. This remote enables users to archive annexed content to tape, track its location, and restore it reliably using the git-annex interface. It leverages a simple on-tape data format optimized for sequential media, featuring:

  • Basic Metadata for each object linked to the git-annex key.
  • Streaming-friendly layout supporting large block sizes and seekable objects.

The remote manages the full data lifecycle: writing files to tape, updating metadata, and retrieving content via SCSI-based positioning. Tape media is treated as append-only and immutable, ensuring data consistency and simplifying recovery. All operations are coordinated through the standard git-annex special remote protocol, with additional logic for tape-specific behaviors.

A live demonstration will showcase real-world usage: initializing a tape remote, archiving data, removing local content, and restoring files from tape. We illustrate how tape-backed storage can be used transparently within annex repositories and how the system handles multiple volumes and offline content. The demo uses standard Linux tools and highlights how the solution integrates into existing workflows without requiring proprietary software.

We conclude with an overview of current limitations—such as lack of random access—and the development roadmap, including support for autoloaders, replication strategies, and enhanced diagnostics. By combining the durability of tape with the flexibility of content-addressable storage, git-annex-remote-tape offers a powerful tool for researchers, archivists, and infrastructure engineers seeking sustainable and auditable archival solutions.