INTRODUCTION
-This is wimlib version 1.6.2 (March 2014). wimlib is a C library for
+This is wimlib version 1.7.0 (June 2014). wimlib is a C library for
creating, modifying, extracting, and mounting files in the Windows Imaging
Format (WIM files). These files are normally created using the ImageX
(imagex.exe) or Dism (Dism.exe) utilities on Windows, but wimlib is distributed
COMPRESSION RATIO
-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 an 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 |
- ===========================================================================
+wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM files.
+wimlib includes its own compression codecs and does not use the compression API
+available on some versions of Windows.
+
+I have gradually been improving the compression codecs in wimlib, and in some
+cases they now outperform and outcompress the equivalent Microsoft
+implementations. Although results will vary depending on the data being
+compressed, in the table below I present the results for a common use case:
+compressing an x86 Windows PE image. Each row displays the compression type,
+the size of the resulting WIM file in bytes, and how many seconds it took to
+create the file. When applicable, the results with the equivalent Microsoft
+implementation in WIMGAPI is included.
+
+ =============================================================================
+ | Compression type || wimlib (v1.7.0) | WIMGAPI (Windows 8.1) |
+ =============================================================================
+ | None [1] || 361,182,560 in 7.6s | 361,183,674 in 11.9s |
+ | XPRESS [2] || 138,992,007 in 11.5s | 140,416,657 in 13.9s |
+ | LZX (quick) [3] || 131,428,113 in 15.2s | N/A |
+ | LZX (normal) [4] || 126,807,853 in 58.9s | 127,259,566 in 55.2s |
+ | LZX (slow) [5] || 126,085,971 in 125s | N/A |
+ | LZMS (non-solid) [6] || 122,082,982 in 59.8s | N/A |
+ | LZMS (solid) [7] || 92,171,126 in 260s | 88,742,356 in 556s |
+ =============================================================================
Notes:
[1] '--compress=none' for wimlib-imagex;
- '/compress none' or no option for ImageX.
+ '/compress:none' for DISM.
[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).
+ '/compress:fast' for DISM.
+ Compression chunk size is 32768 bytes, 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).
+ [3] No compression option specified to wimlib-imagex;
+ no known equivalent for DISM.
+ Compression chunk size is 32768 bytes, 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).
+ '/compress:maximum' for DISM.
+ Compression chunk size is 32768 bytes, 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).
+ no known equivalent for DISM.
+ Compression chunk size is 32768 bytes, 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.
+ no known equivalent for DISM.
+ Compression chunk size is 131072 bytes, the default for LZMS.
[7] '--compress=recovery --solid' or '--compress=LZMS --solid' 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.
+ wimlib-imagex. Should be '/compress:recovery' for DISM, but it doesn't
+ work; I called WIMGAPI directly instead.
+ Compression chunk size in solid blocks is 67108864 bytes in both cases.
+
+I did the timings on Windows 8.1 running in a virtual machine so that
+side-by-side comparisons with the Microsoft implementation would be possible.
+However, do note that wimlib may have even better performance on other operating
+systems such as Linux. I used the 64-bit builds of both programs.
+
+The compression ratio provided by wimlib is also competitive with commonly used
+archive formats. Below are file sizes that result when the Canterbury corpus is
+compressed with wimlib (v1.7.0), WIMGAPI (Windows 8), and some other
+formats/programs:
=================================================
| Format | Size (bytes) |
| 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 |
+ | WIM (wimlib, LZX normal) | 649,204 |
+ | WIM (wimlib, LZX slow) | 639,618 |
+ | WIM (wimlib, LZMS non-solid) | 592,136 |
| 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 (wimlib, LZMS solid) | 525,270 |
+ | WIM (wimlib, LZMS solid, slow) | 521,700 |
| WIM (WIMGAPI, LZMS solid) | 521,232 |
| tar.xz (xz, default) | 486,916 |
| tar.xz (xz, -9) | 486,904 |
| 7z (7-zip, -9) | 483,239 |
=================================================
+Note: WIM does even better on directory trees containing duplicate files, which
+the Canterbury corpus doesn't have.
+
NTFS SUPPORT
WIM images may contain data, such as alternate data streams and
For both platforms the code for NTFS capture and extraction is complete enough
that it is possible to apply an image from the "install.wim" contained in recent
-Windows installation media (Vista, Windows 7, or Windows 8) directly to a NTFS
+Windows installation media (Vista, Windows 7, or Windows 8) directly to an NTFS
filesystem, and then boot Windows from it after preparing the Boot Configuration
Data. In addition, a Windows installation can be captured (or backed up) into a
WIM file, and then re-applied later.
from libcrypto (part of OpenSSL). The default is to use libcrypto if it
is found on the system.
---enable-xattr, --disable-xattr
- Enable or disable support for the extended-attributes interface to NTFS
- alternate data streams in mounted WIMs. To support these, wimlib
- requires that the setxattr() function and the attr/xattr.h header are
- available. The default is to autodetect whether support is possible.
-
--disable-multithreaded-compression
By default, data will be compressed using multiple threads when writing
a WIM, unless only 1 processor is detected. Specify this option to
http://www.tuxera.com/community/ntfs-3g-download/ for more information.
The LZX decompressor (lzx-decompress.c) was originally based on code from the
-cabextract project (http://www.cabextract.org.uk) but has been rewritten.
+cabextract project (http://www.cabextract.org.uk). The LZX compressor
+(lzx-compress.c) was originally based on code written by Matthew Russotto
+(www.russotto.net/chm/). However I have since rewritten and made many
+improvements to both the decompressor and compressor.
-The LZX compressor (lzx-compress.c) was originally based on code written by
-Matthew Russotto (www.russotto.net/chm/) but has been rewritten. It now uses
-suffix array construction code from divsufsort
-(https://code.google.com/p/libdivsufsort/) and algorithms from 7-Zip as well as
-several published papers.
+lz_hash.c contains LZ77 match-finding code that uses hash chains. It is based
+on code from zlib but I have since rewritten it.
-lz_hash.c contains a hash-table-based LZ77 matchfinder that is based on code
-from zlib but has been rewritten. This code is applicable to XPRESS, LZX, and
-LZMS, all of which are partly based on LZ77 compression.
+lz_bt.c contains LZ77 match-finding code that uses binary trees. It is based on
+code from liblzma but I have since rewritten it.
A limited number of other free programs can handle some parts of the WIM
file format:
other archive formats). However, wimlib is designed specifically to handle
WIM files and provides features previously only available in Microsoft's
implementation, such as the ability to mount WIMs read-write as well as
- read-only, the ability to create LZX or XPRESS compressed WIMs, and the
- correct handling of security descriptors and hard links.
+ read-only, the ability to create compressed WIMs, and the correct handling
+ of security descriptors and hard links.
* ImagePyX (https://github.com/maxpat78/ImagePyX) is a Python program that
provides similar capabilities to wimlib-imagex. One thing to note, though,
is that it does not support compression and decompression by itself, but
instead relies on external native code, such as the codecs from wimlib.
-A very early version of wimlib is being used to deploy Windows 7 from the
-Ultimate Deployment Appliance. For more information see
-http://www.ultimatedeployment.org/.
-
-If you are looking for a UNIX archive format that provides features similar to
-WIM, I recommend you take a look at SquashFS (http://squashfs.sourceforge.net/).
+If you are looking for an archive format that provides features similar to WIM
+but was designed primarily for UNIX, you may want to consider SquashFS
+(http://squashfs.sourceforge.net/). However, you may find that wimlib works
+surprisingly well on UNIX. It will store hard links and symbolic links, and it
+has optional support for storing UNIX owners, groups, modes, and special files
+such as device nodes and FIFOs. Actually, I use it to back up my own files on
+Linux!
- LICENSE
+ LICENSE AND DISCLAIMER
-As of version 1.0.0, wimlib and all programs and scripts distributed with it are
-released under the GNU GPL version 3.0 or later.
+See COPYING for information about the license.
wimlib is independently developed and does not contain any code, data, or files
copyrighted by Microsoft. It is not known to be affected by any patents.
implementation with built-in code and there will be no difference in
functionality.
- DISCLAIMER
-
wimlib comes with no warranty whatsoever. Please submit a bug report (to
ebiggers3@gmail.com) if you find a bug in wimlib and/or wimlib-imagex.
git://wimlib.net / wimlib / blobdiff