This example demonstrates how to prune a repository to reclaim space and optimize storage. Pruning removes unused data, repacks fragmented data, and applies retention policies to remove old snapshots.
Complete Example
use rustic_backend::BackendOptions;
use rustic_core::{Credentials, PruneOptions, Repository, RepositoryOptions};
use simplelog::{Config, LevelFilter, SimpleLogger};
use std::error::Error;
fn main() -> Result<(), Box<dyn Error>> {
// Display info logs
let _ = SimpleLogger::init(LevelFilter::Info, Config::default());
// Initialize Backends
let backends = BackendOptions::default()
.repository("/tmp/repo")
.to_backends()?;
// Open repository
let repo_opts = RepositoryOptions::default();
let repo = Repository::new(&repo_opts, &backends)?.open(&Credentials::password("test"))?;
let prune_opts = PruneOptions::default();
let prune_plan = repo.prune_plan(&prune_opts)?;
println!("{:?}", prune_plan.stats);
println!("to repack: {:?}", prune_plan.repack_packs());
// to run the plan uncomment this line:
// prune_plan.do_prune(&repo, &prune_opts)?;
Ok(())
}
Step-by-Step Explanation
1. Set up logging
let _ = SimpleLogger::init(LevelFilter::Info, Config::default());
let backends = BackendOptions::default()
.repository("/tmp/repo")
.to_backends()?;
3. Open the repository
let repo_opts = RepositoryOptions::default();
let repo = Repository::new(&repo_opts, &backends)?.open(&Credentials::password("test"))?;
let prune_opts = PruneOptions::default();
- Repack pack files that are less than 80% used
- Remove unreferenced data
- Optimize pack file sizes
5. Create a prune plan
let prune_plan = repo.prune_plan(&prune_opts)?;
- Identifies unused data blobs
- Finds fragmented pack files to repack
- Calculates how much space can be reclaimed
- Determines which operations are needed
Important: Creating a plan doesn’t modify the repository - it’s safe and non-destructive.
6. Review the plan
println!("{:?}", prune_plan.stats);
println!("to repack: {:?}", prune_plan.repack_packs());
- stats: Statistics about data to be removed or repacked
- repack_packs(): List of pack files that will be reorganized
Reviewing the plan helps you understand the impact before making changes.
7. Execute the plan
// prune_plan.do_prune(&repo, &prune_opts)?;
- Remove unused data blobs
- Repack fragmented pack files
- Delete old pack files
- Update the index
- Reclaim storage space
Warning: Pruning modifies the repository and removes data. Always ensure you have:
- A recent backup or repository copy
- No concurrent backup operations running
- Sufficient disk space for repacking operations
Expected Output
When creating a prune plan, you’ll see analysis results:
PruneStats {
packs_to_keep: 45,
packs_to_repack: 8,
packs_to_remove: 3,
size_to_remove: 145678912, // ~139 MB
size_to_repack: 523456789, // ~499 MB
size_after_prune: 2147483648, // ~2.0 GB
blobs_unused: 1234,
}
to repack: [
"5e6f7g8h9i0j1k2l",
"3m4n5o6p7q8r9s0t",
...
]
do_prune), you’ll see progress:
INFO - starting prune operation
INFO - processing 8 pack files for repacking
INFO - repacked: 1/8 (62.4 MB)
INFO - repacked: 4/8 (249.8 MB)
INFO - repacked: 8/8 (499.2 MB)
INFO - removing 3 unused pack files
INFO - removed 139 MB
INFO - updating index
INFO - prune completed: reclaimed 139 MB, optimized 499 MB
Advanced Configuration
Custom Repack Threshold
// Repack pack files that are less than 50% utilized
let prune_opts = PruneOptions::default()
.max_unused("50%");
Limit Repacking Size
// Don't repack more than 1GB of data
let prune_opts = PruneOptions::default()
.max_repack("1GB");
Keep Pack Files Above Size Threshold
// Don't repack pack files larger than 100MB
let prune_opts = PruneOptions::default()
.repack_cacheable_only(true);
Dry Run Mode
Always review the plan before executing:
let prune_plan = repo.prune_plan(&prune_opts)?;
// Review statistics
if prune_plan.stats.size_to_remove > 1_000_000_000 {
println!("Warning: Would remove more than 1GB");
// Decide whether to proceed
}
// Only proceed if beneficial
if prune_plan.stats.size_to_remove > 100_000_000 {
prune_plan.do_prune(&repo, &prune_opts)?;
} else {
println!("Skipping prune: minimal benefit");
}
When to Prune
After Removing Snapshots
When you delete old snapshots with forget, the data remains in the repository. Prune removes it:
// First, forget old snapshots
let forget_opts = ForgetOptions::default()
.keep_last(10);
repo.forget(&forget_opts)?;
// Then prune to reclaim space
let prune_plan = repo.prune_plan(&PruneOptions::default())?;
prune_plan.do_prune(&repo, &PruneOptions::default())?;
Regular Maintenance
Schedule pruning based on repository activity:
- High activity (daily backups): Prune weekly
- Medium activity (weekly backups): Prune monthly
- Low activity (monthly backups): Prune quarterly
Signs You Need to Prune
- Repository size keeps growing despite stable data
- Many snapshots have been deleted
- Backup performance has degraded
- You see warnings about fragmented pack files
Best Practices
Always create a prune plan and review the statistics before executing. This helps you understand the impact and catch any unexpected changes.
Safe Pruning Workflow
-
Check repository first:
repo.check(CheckOptions::default())?;
-
Create and review plan:
let plan = repo.prune_plan(&prune_opts)?;
println!("Will reclaim: {} bytes", plan.stats.size_to_remove);
-
Execute prune:
plan.do_prune(&repo, &prune_opts)?;
-
Verify integrity after:
repo.check(CheckOptions::default())?;
For large repositories:
let prune_opts = PruneOptions::default()
.max_repack("5GB") // Limit work per run
.fast_repack(true); // Optimize for speed
Error Handling
match prune_plan.do_prune(&repo, &prune_opts) {
Ok(_) => {
println!("Prune completed successfully");
}
Err(e) => {
eprintln!("Prune failed: {}", e);
// Common errors:
// - Insufficient disk space for repacking
// - Repository locked by another process
// - Network errors with remote backend
// - Corrupted pack files
// Run check to verify repository integrity
repo.check(CheckOptions::default())?;
}
}
Next Steps
