INTRODUCTION
-This is wimlib version 1.6.0 (January 2014). wimlib is a C library for
+This is wimlib version 1.7.1-BETA (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
A WIM file may be either stand-alone or split into multiple parts. Split WIMs
are read-only and cannot be modified.
+Since version 1.6.0, wimlib also supports ESD (.esd) files, except when
+encrypted. These are still WIM files but they use a newer version of the file
+format.
+
IMAGEX IMPLEMENTATION
wimlib itself is a C library, and it provides a documented public API (See:
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 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' for DISM.
+
+ [2] '--compress=fast' or '--compress=XPRESS' for wimlib-imagex;
+ '/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 DISM.
+ Compression chunk size is 32768 bytes, the default for LZX.
+
+ [4] '--compress=maximum' or '--compress=LZX' for wimlib-imagex;
+ '/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 DISM.
+ Compression chunk size is 32768 bytes, the default for LZX.
+
+ [6] '--compress=recovery' or '--compress=LZMS' for wimlib-imagex;
+ 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. 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) |
+ =================================================
+ | 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) | 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) | 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, default) | 484,700 |
+ | 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
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.
-lz77.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 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!
-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/).
+ LICENSE AND DISCLAIMER
- LICENSE
-
-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