# Test Case: zstd Compression Level 22

**Test ID**: TC107-zstd-level22  

**G5 fixture contract**: Use [G5-MANUAL-SETUP.md](G5-MANUAL-SETUP.md).
Its generated paths, source comparisons, structured corruption offsets, and
cleanup rules supersede placeholder examples in this file.
**Category**: Compression  
**Priority**: Medium  
**Regression**: None

## Objective
Verify zstd compressed data path with level 22 (maximum) compression.

## Preconditions
- EROFS image created with zstd level 22: `mkfs.erofs -zzstd,level=22 test.img src/`
- Large test files (multi-MB)
- FreeBSD 13.0+ with libzstd

## Test Steps
1. Create image with zstd level 22 compression
2. Attach and mount: `unit=$(mdconfig -a -t vnode -f test.img); mount -t erofs -o ro /dev/${unit} /mnt`
3. Read large files sequentially
4. Test random access
5. Monitor memory usage during decompression

## Expected Results
- All files decompress correctly
- Maximum compression ratio for zstd
- Acceptable decompression speed
- Stable memory usage

## Verification Method
- Checksums match original files
- Compression ratio > level 15
- Decompression throughput > 100 MB/s
- No memory leaks

## Cleanup
```sh
umount /mnt
mdconfig -d -u "${unit}"
```

## Notes
Tests feature 59: zstd compressed data path with maximum compression.