On Thu, Jun 3, 2021 at 12:20 PM Jon LaBadie <jonfu(a)jgcomp.com> wrote:
On my 3 systems, F34, F34, and CentOS7, they are
1, 2, and 6 years old respectively.
Are old rescue kernels still useful? (6 years?)
They might be useful to a sysadmin, I think they are useless. The
rescue kernel is really just a "no host-only" initramfs that contains
a bunch of extra dracut and kernel modules that the host only
initramfs doesn't. The difficulty is the rescue initramfs can't do a
full graphical boot once /usr/lib/modules/ dir for that kernel has
been removed, which was likely in its first 4 weeks following
installation.
Since you won't get graphical boot anyway, I'm not sure you have a
good chance of dracut building a new host only initramfs that
contains the driver needed for whatever new hardware you've added or
changed to. It's pretty esoteric landing in a dracut shell even for
experienced users. So I am not a fan.
What I would like to see is (a) an initramfs that can boot a graphical
stack (b) contains the Live OS dracut modules (c) and overlayfs, and
wire it up so that the rescue boot entry does a read-only sysroot boot
+ writable overlay like a LiveOS. So now folks can use a web browser
normally, get on irc or whatever, and get some help with why they
can't boot without having to resort to mobile or a 2nd computer they
may not have handy.
A side plus for Btrfs cases, it has a unique ro,rescue=all mount
option that tolerates file system problems. Plausibly we can still
boot read-only in situations where other file systems would face plant
until they get an fsck. Whereas on Btrfs we really want to steer folks
towards freshening backups before they attempt a repair, if they end
up in a disaster situation. But nevertheless, such an effort would be
generically beneficial no matter the file system.
A variation on that might be a read-only "rescue" or "recovery"
snapshot that would be immutable, paired with the same
LiveOS+overlayfs concept. That way a boot is possible in a variety of
other more likely user error or update related scenarios, i.e. file
system isn't damaged, it's the installation that's messed up, and what
you need is a live boot but don't have a USB stick handy, so just bake
it into a small snapshot. *shrug* maybe. We could make it completely
self contained including the kernel, initramfs, and the whole graphics
stack. But, near term such a thing would be btrfs only unless we
dedicate a literal partition and stick a Live OS ISO image on it
(effectively).
--
Chris Murphy