parsync

parsync is a high-throughput, resumable pull sync from SSH remotes, with parallel file transfers and optional block-delta sync.

Installation

Download the binary for your platform from the releases page, or install from source:

make build
make install

Platform support

• Linux: x86_64-unknown-linux-gnu, aarch64-unknown-linux-gnu
• macOS: aarch64-apple-darwin, x86_64-apple-darwin
• Windows: x86_64-pc-windows-msvc (best-effort metadata support)

Usage

parsync -vrPlu user@example.com:/remote/path /local/destination

With non-default SSH port:

parsync -vrPlu user@example.com:2222:/remote/path /local/destination

SSH config host aliases are supported.

Performance tuning

parsync -vrPlu --jobs 16 --chunk-size 16777216 --chunk-threshold 134217728 user@host:/src /dst

Balanced mode defaults:

• no per-file sync_all barriers (atomic rename preserved)
• existing-file digest checks are skipped unless requested
• chunk completion state is committed in batches
• post-transfer remote mutation stat check is skipped (enabled in strict mode)

Throughput flags:

• --strict-durability: enable fsync-heavy strict mode
• --verify-existing: hash existing files before skip decisions
• --sftp-read-concurrency: parallel per-file read requests for large files
• --sftp-read-chunk-size: read request size for SFTP range pulls

Notes on Windows metadata behavior

• -A, -X: warn and continue (unsupported)
• -o, -g: warn and continue (unsupported)
• -p: best-effort (readonly mapping), then continue
• -l: attempts symlink creation; if OS/privilege disallows it, symlink is skipped with warning

Enable strict mode to hard-fail on unsupported behavior:

parsync --strict-windows-metadata -vrPlu user@host:/src C:\\dst

Windows symlink troubleshooting

Windows symlink creation usually requires one of:

• Administrator privileges
• Developer Mode enabled

If not available, -l may skip symlinks (or fail with --strict-windows-metadata).