VRAMLab publication log Experiment: WSL2 VHDX host attributes vs launch and --manage --resize Date: 2026-08-11 (Asia/Seoul) SCOPE ----- This is a sanitized publication log derived from the preserved JSON and CSV records. It contains no production-distro path. The measured runtime was WSL 2.7.3.0; results are not presented as measurements of later WSL versions. ENVIRONMENT ----------- Windows: Windows 11 Home 25H2, build 26200.8875 WSL: 2.7.3.0 Kernel: 6.6.114.1-1 (wsl --version) Uname release: 6.6.114.1-microsoft-standard-WSL2 Guest: Ubuntu 26.04 LTS Host storage: C: SSD, NTFS Base VHDX: 6,548,357,120 bytes logical and allocated Base SHA-256: 3131EF600699A5FDAD281B4ED36ECE29AE0868015A1AC0C483E7BC3F06D8C802 Resize target: 1100GB = 1,181,116,006,400 bytes (1100 GiB) Initial ext4 total from df -B1 /: 1,081,101,176,832 bytes DESIGN ------ The production Ubuntu distro was exported once. Every valid run used an independent disposable clone from that base. Startup and resize were separate cohorts: four conditions x three clones = 12 startup runs and 12 resize runs. Conditions: control Archive compressed Archive, Compressed raw-sparse Archive, SparseFile, set with fsutil sparse setflag managed-sparse Archive, SparseFile, set with WSL --set-sparse true Before host-file mutation, WSL was shut down and the running-distro list was confirmed empty. File length, allocated bytes, attributes, and SHA-256 were recorded around condition setup. All 24 pre-condition/condition hash checks passed. fsutil sparse setrange was never used. Startup probe: wsl.exe -d --exec /bin/true Resize probe: wsl.exe --manage --resize 1100GB STARTUP RUNS ------------ case rep exit seconds allocated after set allocated after boot control R1 0 2.366 6,548,357,120 6,548,357,120 control R2 0 2.432 6,548,357,120 6,548,357,120 control R3 0 2.372 6,548,357,120 6,548,357,120 compressed R1 0 2.308 4,956,442,624 4,956,499,968 compressed R2 0 2.129 4,956,438,528 4,956,495,872 compressed R3 0 2.166 4,956,434,432 4,956,491,776 raw-sparse R1 0 2.628 6,548,357,120 6,547,963,904 raw-sparse R2 0 2.468 6,548,357,120 6,548,357,120 raw-sparse R3 0 2.585 6,548,357,120 6,548,357,120 managed-sparse R1 0 2.533 6,548,357,120 6,548,357,120 managed-sparse R2 0 2.471 6,548,357,120 6,548,357,120 managed-sparse R3 0 2.347 6,548,357,120 6,548,357,120 Startup result: 12/12 successful. These are launch probes, not long-running workload or performance measurements. RESIZE RUNS ----------- case rep first exit first sec exact code clear sec retry exit retry sec post-boot control R1 0 4.626 no n/a n/a n/a 0 control R2 0 4.942 no n/a n/a n/a 0 control R3 0 4.926 no n/a n/a n/a 0 compressed R1 -1 0.069 yes 15.637 0 5.376 0 compressed R2 -1 0.062 yes 13.123 0 4.930 0 compressed R3 -1 0.058 yes 9.541 0 4.958 0 raw-sparse R1 -1 0.084 yes 0.027 0 5.400 0 raw-sparse R2 -1 0.063 yes 0.021 0 4.901 0 raw-sparse R3 -1 0.082 yes 0.024 0 4.899 0 managed-sparse R1 -1 0.187 yes 0.058 0 5.380 0 managed-sparse R2 -1 0.058 yes 0.055 0 4.942 0 managed-sparse R3 -1 0.058 yes 0.054 0 4.963 0 Exact observed output on the Korean Windows locale, all nine conditioned resize failures: 가상 디스크 시스템 제한으로 인해 요청한 작업을 완료할 수 없습니다. 가상 하드 디스크 파일은 압축이 풀려 있는 상태이고 암호화되지 않아야 하며 스파스가 아니어야 합니다. 오류 코드: Wsl/Service/0xc03a001a The canonical Win32 constant is ERROR_VIRTUAL_DISK_LIMITATION (0xC03A001A). The English wording was not captured locally and is not represented as local output in this log. RECOVERY -------- The matching condition was cleared, then the identical resize target was retried: compressed: compact.exe /u /f /a raw-sparse: fsutil.exe sparse setflag 0 managed-sparse: wsl.exe --manage --set-sparse false Recovery resize: 9/9 successful. Post-recovery launch and df: 9/9 successful. Post-resize ext4 total: 1,161,425,506,304 bytes. Increase: 80,324,329,472 bytes = 74.808 GiB. No Windows reboot was used; wsl --shutdown was sufficient on this host. CAPACITY OBSERVATIONS --------------------- Resize-cohort NTFS compression, n=3: allocated before: 6,548,357,120 bytes allocated after median: 4,956,434,432 bytes median saved: 1,591,922,688 bytes = 1.48 GiB = 24.31% compact /c median: 65.285 seconds compact /u median: 13.123 seconds Raw sparse setflag, startup cohort n=3: saved immediately: median 0 bytes, range 0-0 saved after one boot: median 0 bytes, range 0-393,216 EFS --- EFS was not tested on a VHDX. A small cipher.exe /e probe returned exit 1 and "The request is not supported" on this Windows Home host. Encryption must not be counted as a failed measured condition. LIMITS AND EXCLUSIONS --------------------- Single PC, single NTFS SSD, WSL 2.7.3, one Ubuntu image, n=3 per condition. Not tested: EFS VHDX, ReFS, network storage, combined attributes, cold reboot, later WSL versions, long-running guest workload, or long-term integrity in the conditioned states. File length and allocated bytes did not change across the failed resize, but a separate immediately-before/immediately-after failure hash was not recorded; no bit-for-bit non-mutation claim is made. One preparation run was excluded after the harness mishandled a \\?\ path prefix. It was safely unregistered, corrected, and preserved separately. It is not counted in the 24 primary runs. FINAL SAFETY CHECK ------------------ All disposable clones were unregistered and their clone files removed. Only the production Ubuntu distro remained registered. Its final /bin/true probe returned exit 0, no WSL distro remained running, and C: had 182,117,838,848 bytes (169.61 GiB) free.