Benchmark numbers for Windows 22H2 in Dec 2022, using ReFS.
Machine was a physical 8/16-core with NVMe. Disable Write Cache Flush flag = Disabled (OS default). All copies done on files with size set via file extents (no data written).
16MB files are about 35X performance, 1MB at 3.2X, and small sizes at about 1.3X.
| Method | FileSize | Mean | Error | StdDev | Median | Ratio | RatioSD |
|---|---|---|---|---|---|---|---|
| File.Copy | 0 | 205.5 us | 8.82 us | 26.01 us | 200.1 us | 1.00 | 0.00 |
| CoW | 0 | 183.7 us | 4.85 us | 14.16 us | 181.9 us | 0.91 | 0.13 |
| File.Copy | 1 | 307.9 us | 6.69 us | 19.53 us | 306.7 us | 1.00 | 0.00 |
| CoW | 1 | 265.5 us | 15.18 us | 44.77 us | 265.6 us | 0.87 | 0.15 |
| File.Copy | 1024 | 310.3 us | 6.56 us | 18.82 us | 310.4 us | 1.00 | 0.00 |
| CoW | 1024 | 235.1 us | 9.51 us | 26.82 us | 227.9 us | 0.76 | 0.10 |
| File.Copy | 16384 | 295.5 us | 5.80 us | 15.39 us | 295.2 us | 1.00 | 0.00 |
| CoW | 16384 | 272.4 us | 16.46 us | 46.96 us | 275.9 us | 0.95 | 0.16 |
| File.Copy | 262144 | 425.5 us | 9.29 us | 26.80 us | 423.8 us | 1.00 | 0.00 |
| CoW | 262144 | 234.6 us | 7.83 us | 22.96 us | 232.7 us | 0.55 | 0.06 |
| File.Copy | 1048576 | 851.7 us | 20.00 us | 56.08 us | 836.3 us | 1.00 | 0.00 |
| CoW | 1048576 | 273.7 us | 15.39 us | 45.39 us | 269.9 us | 0.33 | 0.06 |
| File.Copy | 16777216 | 9,327.9 us | 179.64 us | 206.88 us | 9,282.0 us | 1.00 | 0.00 |
| CoW | 16777216 | 273.3 us | 15.22 us | 44.17 us | 260.5 us | 0.04 | 0.00 |
| Method | FileSize | Mean | Error | StdDev | Median | Ratio | RatioSD |
|---|---|---|---|---|---|---|---|
| File.Copy | 0 | 202.8 us | 6.79 us | 19.92 us | 199.5 us | 1.00 | 0.00 |
| CoW | 0 | 192.8 us | 5.40 us | 15.57 us | 191.2 us | 0.96 | 0.12 |
| File.Copy | 1 | 346.8 us | 9.65 us | 27.99 us | 345.8 us | 1.00 | 0.00 |
| CoW | 1 | 237.5 us | 7.38 us | 21.28 us | 239.3 us | 0.69 | 0.08 |
| File.Copy | 1024 | 372.9 us | 9.75 us | 27.66 us | 371.2 us | 1.00 | 0.00 |
| CoW | 1024 | 248.0 us | 6.97 us | 20.21 us | 248.5 us | 0.67 | 0.07 |
| File.Copy | 16384 | 347.1 us | 12.56 us | 35.62 us | 342.2 us | 1.00 | 0.00 |
| CoW | 16384 | 248.8 us | 9.76 us | 28.47 us | 244.3 us | 0.72 | 0.11 |
| File.Copy | 262144 | 484.3 us | 11.83 us | 34.69 us | 482.4 us | 1.00 | 0.00 |
| CoW | 262144 | 247.8 us | 8.51 us | 24.69 us | 245.6 us | 0.51 | 0.06 |
| File.Copy | 1048576 | 954.4 us | 19.06 us | 41.85 us | 948.0 us | 1.00 | 0.00 |
| CoW | 1048576 | 251.3 us | 9.77 us | 28.64 us | 246.8 us | 0.27 | 0.03 |
| File.Copy | 16777216 | 9,867.2 us | 195.87 us | 546.01 us | 9,605.5 us | 1.00 | 0.00 |
| CoW | 16777216 | 283.5 us | 6.56 us | 18.60 us | 282.7 us | 0.03 | 0.00 |