Svn2Svn Best Practices: Step-by-Step Workflow for Reliable Transfers

Troubleshooting Svn2Svn: Common Errors and Fixes

Migrating or replicating Subversion repositories with Svn2Svn can save time, but issues do occur. Below are common errors, diagnostic steps, and clear fixes so you can get your migration back on track quickly.

1. Authentication failures

• Symptoms: “Authentication required”, “403 Forbidden”, or repeated credential prompts.
• Cause: Incorrect credentials, expired tokens, or mismatched auth methods between source and target.
• Fix:
  1. Verify username/password by logging into both SVN servers with a standard SVN client.
  2. If using token-based or SSPI/Kerberos auth, confirm tokens are valid and the Svn2Svn process runs under an account with proper privileges.
  3. For scripted runs, store credentials in a secure credentials file or use an authenticated SVN wrapper; ensure file permissions prevent access by other users.

2. Network timeouts and connection drops

• Symptoms: “Connection reset by peer”, timeouts during large transfers.
• Cause: Intermittent network issues, large repository transfers exceeding default timeouts, or proxy interruptions.
• Fix:
  1. Test connectivity with ping/traceroute to source and target servers.
  2. Increase network/timeouts in Svn2Svn or the underlying SVN client configuration (e.g., HTTP/WebDAV timeout settings).
  3. Enable resumption or chunked replication if supported; otherwise split migration into smaller paths (per-project or per-branch).

3. Incomplete revision history or missing tags/branches

• Symptoms: Certain revisions, branches, or tags absent after migration.
• Cause: Filter rules, path mappings, or incorrect include/exclude patterns; repository layout differences.
• Fix:
  1. Review Svn2Svn mapping configuration for stray exclude rules or incorrect source-to-target path mappings.
  2. Re-run a dry-run or preview mode to confirm which revisions would be transferred.
  3. If history was partially migrated, use a targeted re-sync for missing paths or revisions, preserving revision order.

4. Revision number conflicts and collisions

• Symptoms: Overlapping revision numbers, unexpected svn:mergeinfo, or broken merges post-migration.
• Cause: Directly copying revisions between repositories that already have revisions, or improper UUID handling.
• Fix:
  1. Ensure destination repository UUIDs and revision sequences are handled consistently—prefer creating a fresh target repo when exact history is required.
  2. If merging into an existing repo, use Svn2Svn options that rewrite or remap revision metadata safely.
  3. After migration, run svnadmin verify and inspect svn:mergeinfo; clean up incorrect mergeinfo entries as necessary.

5. Repository UUID mismatch

• Symptoms: Clients complain about repository UUID differences; checkouts fail.
• Cause: Source and target repositories have different UUIDs but identical contents.
• Fix:
  1. Decide whether to keep source UUID or accept a new one. To reuse source UUID on the target, use svnadmin setuuid (run on the target server) with caution.
  2. Inform users to switch working copies or perform fresh checkouts if UUID changes are unavoidable.

6. Hooks and server-side customizations not migrated

• Symptoms: Post-commit hooks, access controls, or custom scripts missing on the target.
• Cause: Hooks and server configs live outside repository dump/restore processes and are not transferred by default.
• Fix:
  1. Manually copy hook scripts from source repository hooks/ directory and adjust paths and permissions.
  2. Recreate server config (authz, apache/nginx configs) and test hooks in a staging environment.

7. File encoding, property, or EOL issues

• Symptoms: Binary files corrupted, svn:eol-style or svn:mime-type lost or altered.
• Cause: Misapplied filters during dump/load or incorrect client settings.
• Fix:
  1. Ensure prop-preservation is enabled in Svn2Svn; use svnadmin dump/load when possible since they preserve properties reliably.
  2. Verify problematic files by exporting from source and comparing checksums with target copies.

8. Disk space and quota errors

• Symptoms: “No space left on device”, failed writes during migration.
• Cause: Insufficient disk space for dump files, temporary files, or final repository.
• Fix:
  1. Check free space on source and target filesystems; clean temp directories.
  2. Use streaming dump/load to avoid large intermediate files or perform incremental transfers.
  3. Monitor disk usage during long migrations and expand quotas as needed.

9. Performance bottlenecks

• Symptoms: Very slow transfers, high CPU or I/O on servers.
• Cause: Single-threaded migration, slow storage, or network bottlenecks.
• Fix:
  1. Run migration during off-peak hours.
  2. If Svn2Svn supports parallelism, enable multiple streams; otherwise migrate in parallel by repository subpaths.
  3. Improve server I/O (faster disks, caching) and ensure adequate CPU/memory.

10. Unexpected tool crashes or unhandled exceptions

• Symptoms: Svn2Svn process exits with stack traces or unhelpful errors.
• Cause: Unhandled edge cases, corrupt repository data, or bugs in the tool.
• Fix:
  1. Capture full logs and enable verbose/debug mode.
  2. Run svnadmin verify on the source to detect corruption.
  3. Consult tool changelogs and update to the latest stable Svn2Svn release; file a bug report with reproducible steps if needed.

Diagnostic checklist (quick)

1. Reproduce error with verbose logging enabled.
2. Run svnadmin verify on source.
3. Confirm credentials and network reachability.
4. Inspect mappings, filters, and include/exclude rules.
5. Check disk space and server logs (Apache/nginx, SVN).
6. Re-run targeted syncs for missing revisions or paths.

When to recreate the target repository

• Create a fresh target repo when you need an identical, clean history and cannot safely remap revisions or UUIDs. This avoids mergeinfo conflicts and simplifies client rollouts.

When to seek support

• If svnadmin verify reports corruption, Svn2Svn crashes on valid repos, or migrations repeatedly fail despite fixes, gather logs and repository samples, then contact your Svn2Svn vendor or community with: Svn2Svn version, SVN server versions, command used, verbose logs, and a minimal repro.