On Sat, Dec 19, 2015 at 7:59 PM, Frederick Grose <[email protected]> wrote: > This post may be of interest, > http://article.gmane.org/gmane.linux.kernel.initramfs/4308 > > ---------- Forwarded message ---------- > From: Frederick Grose <[email protected]> > Date: Sat, Dec 19, 2015 at 7:51 PM > Subject: OverlayFS support for LiveOS > To: [email protected] > > > See this pull request, https://github.com/haraldh/dracut/pull/107 > and issue discussion, https://github.com/haraldh/dracut/issues/104 > > This may be suitable for rawhide testing, particularly with btrfs and > other filesystems. > > Commit message: > Integrate the option to use an OverlayFS as the root filesystem > into the 90dmsquash-live module for testing purposes. > > Tested primarily with transient, in-RAM overlay boots on vfat- > formatted Live USB devices, with persistent overlay directories > on ext4-formatted Live USB devices, and with embedded, persistent > overlay directories on vfat-formatted devices. (Persistent overlay > directories on a vfat-formatted device must be in an embedded > filesystem that supports the creation of trusted.* extended attributes, > and must provide valid d_type in readdir responses.) The > rd.live.overlay.readonly option to allow a persistent overlayfs to be > mounted read only through a higher level transient overlay directory > has been implemented through the multiple lower layers feature of > OverlayFS. > > This implementation currently requires the enforcing=0 kernel command > line option. Further SELinux tuning may change this limitation. > > To permit easier comparison of Device-mapper vs. OverlayFS performance, > the default transient dm overlay size has been adjusted up to 32 GiB. > A transient dm overlay is a sparse file in memory, so this does not > consume more RAM for legacy applications. It does permit a user to > use all of the available root filesystem storage, and fails gently > when it is consumed, as the available free root filesystem storage on > a typical LiveOS build is under a few GiB. Thus, when booted on other- > than-small RAM systems, the transient dm overlay should not overflow. > > OverlayFS offers the potential to use all of the available free RAM, > or all of the available free disc storage on non-vfat-devices, > in its overlay, even beyond the root filesystem available space, > because the OverlayFS root filesystem is a union of directories on > two different partitions.
Here is a new version of livecd-tools/liveimage-mount <https://github.com/FGrose/livecd-tools/blob/liveimage-mount/tools/liveimage-mount> that supports LiveOS devices with OverlayFS. And here is a new version of livecd-tools/editliveos.py <https://github.com/FGrose/livecd-tools/blob/editliveos/imgcreate/editliveos.py> that supports editing LiveOS images that use OverlayFS.
-- livecd mailing list [email protected] http://lists.fedoraproject.org/admin/lists/[email protected]
