Modern FS Benchmark
Modern FS Benchmark is a free Linux tool for comparing copy-on-write filesystems such as btrfs, ZFS, and bcachefs against ext4 and XFS baselines.
What Modern FS Benchmark is
Modern FS Benchmark is a free Linux tool for comparing copy-on-write filesystems such as btrfs, ZFS, and bcachefs against ext4 and XFS baselines. Its benchmark phases cover throughput, latency, snapshots, compression, reflinks, degraded operation, rebuilding, corruption recovery, and near-full behavior. Results appear in a dashboard with per-metric charts, aging curves, run trends, filters, and a sortable table. GitHub Actions runs benchmarks on each push and every six hours, using loop devices backed by sparse files. Those hosted runs share one virtual disk, so their absolute throughput is not meaningful and RAID striping gains are fictional. The project also documents local Linux runs and supports real block devices, but those runs wipe listed devices; devices must be unmounted, and filesystem signatures require BENCH_WIPE=1. Its corruption test checks a tracked file hash after overwriting a raw range and running a scrub; it is not a whole-filesystem health check. The project uses custom workload recipes and a project-specific summary index rather than an industry-standard methodology.
Good
- Free and available for Linux
- Measures throughput, latency, and IOPS
- Dashboard includes charts and run trends
- Supports local and real-device benchmark runs
- Includes a reusable NixOS module
Watch out
- Hosted CI throughput figures are not meaningful
- Real-device runs wipe listed devices
- Benchmark methodology is project-specific
- Corruption test is not a whole-filesystem health check
Who it suits
Modern FS Benchmark suits Linux users who want to compare filesystem behavior across a range of workloads. It is also suited to operators with dedicated self-hosted GitHub Actions runners, provided they account for destructive real-device runs.
Verdict
Modern FS Benchmark covers many filesystem behaviors and provides a dashboard for inspecting results. Treat hosted CI throughput and its custom summary index with care, and use real-device runs only with the stated wipe requirements in mind.
The facts
Each one read from Modern FS Benchmark's own pages, with the date it was checked.
What it does
- Benchmark coverage
- Its measurements include redundancy layouts, snapshots, compression, encryption, reflinks, fsync latency, degraded operation, rebuilds, corruption recovery, and near-full behavior.checked 4 Oct 2026
- CI cadence
- GitHub Actions runs benchmarks on every push and on a six-hour schedule using four loop devices backed by sparse files.checked 4 Oct 2026
- CI limitation
- Hosted CI devices share one virtual disk, so the project says absolute throughput is meaningless and RAID striping gains are fictional in those runs.checked 4 Oct 2026
- Destructive operation
- Real-device runs require unmounted devices, refuse devices with filesystem signatures unless BENCH_WIPE=1 is set, and wipe listed devices.checked 4 Oct 2026
- Hardware runs
- The scripts can run against real block devices, which are wiped when listed for a benchmark run; devices must be unmounted and existing filesystem signatures require BENCH_WIPE=1.checked 4 Oct 2026
- Hardware support
- The maintainer says a suitable dedicated server currently costs approximately €70 per month, depending on availability and disk configuration, and invites hardware support or sponsorship.checked 4 Oct 2026
- Integrations
- The project runs benchmarks in GitHub Actions and provides a reusable NixOS module and benchmark package for self-hosted runners.checked 4 Oct 2026
- Integrity coverage
- The project describes checksum verification and reconstruction testing for btrfs, ZFS, and bcachefs when redundancy is configured.checked 4 Oct 2026
- Licensing
- Source code, configuration, workflows, and documentation use Apache License 2.0, while published benchmark datasets use CC BY 4.0.checked 4 Oct 2026
- Local use
- The README documents running the benchmark locally on Linux with loop devices or on real block devices.checked 4 Oct 2026
- Maintainer
- The repository copyright identifies Bartosz Fenski; it does not state a headquarters or founding date.checked 4 Oct 2026
- Methodology limitation
- The README says its workload recipes and composite summary index are project-specific rather than an industry-standard benchmark.checked 4 Oct 2026
- Methodology limits
- The exact workload recipes and composite summary index are project-specific rather than an industry-standard benchmark.checked 4 Oct 2026
- Project licenses
- The source code, configuration, workflows, and documentation use Apache License 2.0; published benchmark datasets use CC BY 4.0.checked 4 Oct 2026
- Purpose
- Modern FS Benchmark continuously benchmarks multi-device copy-on-write filesystems, including btrfs, ZFS, and bcachefs, against ext4 and XFS baselines.checked 4 Oct 2026
- Results dashboard
- Results are published in a dashboard with per-metric charts, aging curves, run trends, filters, and a sortable table.checked 4 Oct 2026
- Security and data integrity
- The corruption phase overwrites a raw range on one device, runs a scrub, and compares a tracked test-file hash; the README cautions that this is not a whole-filesystem health check.checked 4 Oct 2026
- Security scope
- The corruption test overwrites a raw range on one device, scrubs, and checks one tracked file hash; it is not a whole-filesystem health check.checked 4 Oct 2026
- Sponsor support
- The maintainer says a suitable dedicated server costs approximately €70 per month and accepts financial support through GitHub Sponsors and Ko-fi.checked 4 Oct 2026
- Support
- The maintainer invites issues and pull requests for workload, configuration, methodology, and filesystem suggestions.checked 4 Oct 2026
- Workloads
- Its benchmark phases measure throughput, latency, snapshots, compression, reflinks, degraded operation and rebuild, corruption recovery, and near-full behavior.checked 4 Oct 2026
Where it runs
- Linux deployment
- The repository provides a Nix flake with a reusable NixOS module and benchmark package for dedicated self-hosted GitHub Actions runners.checked 4 Oct 2026
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