Editing 7z (section)

=== Limitations ===
The 7z format does not store [[filesystem permissions]] (such as [[UNIX]] owner/group permissions or [[NTFS]] [[Access control list|ACL]]s), and hence can be inappropriate for backup/archival purposes. A workaround on UNIX-like systems for this is to convert data to a [[Tar (file format)|tar bitstream]] before compressing with 7z. But GNU tar (common in many UNIX environments) can also compress with the LZMA2 algorithm ("[[XZ Utils|xz]]") natively, without the use of 7z, using the "-J" switch. The resulting file extension is ".tar.xz" or ".txz" and not ".tar.7z". This method of compression has been adopted with many distributions for packaging, such as Arch, Debian (deb), Fedora (rpm) and Slackware. (The older "lzma" format is less efficient.)<ref>{{Cite web|url=https://www.gnu.org/software/tar/manual/html_section/Compression.html|title=GNU tar 1.34: 8.1 Using Less Space through Compression|access-date=17 March 2015|archive-date=2 April 2015|archive-url=https://web.archive.org/web/20150402103628/https://www.gnu.org/software/tar/manual/html_section/Compression.html|url-status=live}}</ref> On the other hand, it is important to note, that tar does not save the filesystem encoding, which means that tar compressed filenames can become unreadable if decompressed on a different computer. 

The 7z format does not allow extraction of some "broken files"—that is (for example) if one has the first segment of a series of 7z files, 7z cannot give the start of the files within the archive—it must wait until all segments are downloaded. The 7z format also lacks recovery records, making it vulnerable to [[data degradation]] unless used in conjunction with external solutions, like [[Parchive|parchives]], or within [[File system|filesystems]] with robust [[Error correction code|error-correction]]. By way of comparison, [[zip (file format)|zip]] files also lack a recovery feature while the [[RAR_(file_format)|rar]] format has one.