use lzma compression
Originally created by Tails on #5295 (Redmine)
As highlighted by grml’s documentation, LZMA compression of the squashfs lowers the generated images’ size by more than 10%.
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Current status
This was implemented in the feature/lzma
Git branch and was merged
into the devel
branch => done in Tails 0.8.
- Linux kernel: Squashfs LZMA support is now in mainline (2.6.38-rcX) in the guise of Squashfs XZ - XZ is LZMA2 which is the successor to LZMA. Current Debian unstable kernels (2.6.39 and later) support it.
- Userspace tools:
squashfs-tools
4.2 adds support for XZ compression. It is available in squeeze-backports. - Debian Live: exporting
MKSQUASHFS_OPTIONS='-comp xz'
into the build environment (inauto/build
) works. - The build documentation now explains how to opt-out from XZ compression.
Test results
Results listed bellow are the resulting ISO images size.
20110423 - devel branch
- default compression: 680MB
- XZ compression: 585MB
Resources
- Debian bug #553707
- discussion on the debian-live/2009/11/msg00031.html@lists.debian.org mailing-list