COMPRESSION RATIO
-wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM archives.
-The following tables compare the compression ratio and performance for creating
-a compressed x86_64 Windows PE image. Note: these timings were done on Windows
-so that the times would be fully comparable; however, wimlib may have even
-better performance on other operating systems such as Linux. Timings were done
-with 2 CPUs available, both of which automatically are used by wimlib for both
-XPRESS and LZX, and also by imagex.exe but apparently only for LZX. Results for
-LZMS compression are excluded because the creation of LZMS compressed WIM
-archives is not yet recommended.
-
- Table 1. WIM size
-
- XPRESS Compression LZX Compression
- wimlib-imagex (v1.5.3): 207,444,390 bytes 188,106,091 bytes
- Microsoft imagex.exe (Windows 7): 209,960,209 bytes 188,224,481 bytes
-
- Table 2. Time to create WIM
-
- XPRESS Compression LZX Compression
- wimlib-imagex (v1.5.3): 73 sec 202 sec
- Microsoft imagex.exe (Windows 7): 90 sec 149 sec
-
-The above LZX data are using explicitly specified maximum compression
-('--compress=maximum') as of wimlib v1.5.3. If `wimlib-imagex capture' or
-`wimlib-imagex capture' is instead run with no '--compress' argument, then a
-faster LZX compressor is used; it will produce results in between those given
-for XPRESS and LZX above.
-
-Note: if the absolute maximum but still compatible (i.e. not changing the
-compression chunk size) LZX compression ratio is desired, `wimlib-imagex
-optimize WIMFILE --recompress --compress-slow' on one of the above
-LZX-compressed WIMs produces a WIM of 187,089,943 bytes in about 400 seconds.
+wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM
+archives. wimlib includes its own compression codecs and does not use the
+compression API available on some versions of Windows. The below table provides
+the results (file size, in bytes, and time to create, in seconds) of capturing a
+WIM containing a x86 Windows PE image, using various compression types and
+options. When applicable, the results with the equivalent Microsoft
+implementation in WIMGAPI, which is the library used by ImageX and Dism, are
+included.
+
+ ===========================================================================
+ | Compression type || wimlib (v1.6.1) | WIMGAPI (Windows 8) |
+ ===========================================================================
+ | None [1] || 531,979,435 in 18s | 531,980,333 in 24s |
+ | XPRESS [2] || 207,369,912 in 22s | 209,886,010 in 39s |
+ | LZX (quick) [3] || 194,876,901 in 29s | N/A |
+ | LZX (normal) [4] || 187,962,713 in 158s | 188,163,523 in 125s |
+ | LZX (slow) [5] || 186,913,423 in 358s | N/A |
+ | LZMS (non-solid) [6] || 176,880,594 in 182s | N/A |
+ | LZMS (solid) [7] || 136,507,304 in 494s | 126,735,608 in 623s |
+ ===========================================================================
+
+Notes:
+ [1] '--compress=none' for wimlib-imagex;
+ '/compress none' or no option for ImageX.
+
+ [2] '--compress=fast' or '--compress=XPRESS' for wimlib-imagex;
+ '/compress fast' or no option for ImageX.
+ Compression chunk size is 32768 (the default for XPRESS).
+
+ [3] No compression option specified to wimlib-imagex; no known equivalent for
+ WIMGAPI (ImageX uses XPRESS compression if no option specified).
+ Compression chunk size is 32768 (the default for LZX).
+
+ [4] '--compress=maximum' or '--compress=LZX' for wimlib-imagex;
+ '/compress maximum' for ImageX.
+ Compression chunk size is 32768 (the default for LZX).
+
+ [5] '--compress=maximum --compress-slow' for wimlib-imagex;
+ no known equivalent for WIMGAPI.
+ Compression chunk size is 32768 (the default for LZX).
+
+ [6] '--compress=recovery' or '--compress=lzms' for wimlib-imagex;
+ no known way to create the equivalent with WIMGAPI.
+ Compression chunk size is 131072 (the default for LZMS). Note: this
+ compression type is not generally recommended due to its limited
+ compatibility with the MS implementations.
+
+ [7] '--compress=recovery --packed-streams' or
+ '--compress=lzms --packed-streams' for wimlib-imagex;
+ WIMCreateFile with WIM_COMPRESSION_LZMS and flag 0x20000000 for WIMGAPI.
+ Compression chunk size in packed resources is 33554432 for wimlib,
+ 67108864 for WIMGAPI. Note: this compression type is not generally
+ recommended due to its limited compatibility with the MS implementations.
+ Also, due to the large chunk size, wimlib uses about 500MB of memory per
+ thread when compressing in this format.
+
+The above timings were done on Windows 8 (x86) so that side-by-side comparisons
+with the Microsoft implementation would be possible; however, wimlib may have
+even better performance on other operating systems such as Linux. The system
+had 2 CPUs and 2 GiB of memory available. All times were done with the page
+cache warmed, so the times primarily measure the performance of the compression
+algorithms and not the time to read data from disk, which presumably is similar
+in each implementation.
+
+Below are results for compressing the Canterbury corpus using wimlib (v1.6.1),
+WIMGAPI (Windows 8), and some other formats/programs, including the archive size
+only. Note that the Canterbury corpus includes no duplicate files or hard
+links, which WIM handles better than most other formats by storing only distinct
+data streams.
+
+ =================================================
+ | Format | Size (bytes) |
+ =================================================
+ | tar | 2,826,240 |
+ | WIM (WIMGAPI, None) | 2,814,278 |
+ | WIM (wimlib, None) | 2,813,856 |
+ | WIM (WIMGAPI, XPRESS) | 825,410 |
+ | WIM (wimlib, XPRESS) | 792,024 |
+ | tar.gz (gzip, default) | 738,796 |
+ | ZIP (Info-Zip, default) | 735,334 |
+ | tar.gz (gzip, -9) | 733,971 |
+ | ZIP (Info-Zip, -9) | 732,297 |
+ | WIM (wimlib, LZX quick) | 722,196 |
+ | WIM (WIMGAPI, LZX) | 651,766 |
+ | WIM (wimlib, LZX normal) | 639,464 |
+ | WIM (wimlib, LZX slow) | 633,144 |
+ | WIM (wimlib, LZMS non-solid) | 590,252 |
+ | tar.bz2 (bzip, default) | 565,008 |
+ | tar.bz2 (bzip, -9) | 565,008 |
+ | WIM (wimlib, LZMS solid) | 534,218 |
+ | WIM (wimlib, LZMS solid, slow) | 529,904 |
+ | WIM (WIMGAPI, LZMS solid) | 521,232 |
+ | tar.xz (xz, default) | 486,916 |
+ | tar.xz (xz, -9) | 486,904 |
+ | 7z (7-zip, default) | 484,700 |
+ | 7z (7-zip, -9) | 483,239 |
+ =================================================
NTFS SUPPORT
git://wimlib.net / wimlib / blobdiff