On Tue, Jun 2, 2015 at 11:52 AM, Neal Becker <ndbecker2(a)gmail.com> wrote:
I think this may be all I need:
sudo mount /dev/sda3 /mnt
[nbecker@nbecker2 ~]$ ls -l /mnt
total 0
drwxr-xr-x. 1 root root 14 Jun 1 18:46 home
dr-xr-xr-x. 1 root root 172 Jun 2 09:39 root
[nbecker@nbecker2 ~]$ sudo btrfs sub snap /mnt/root /mnt/root-f21
Create a snapshot of '/mnt/root' in '/mnt/root-f21'
[nbecker@nbecker2 ~]$ ls -l /mnt
total 0
drwxr-xr-x. 1 root root 14 Jun 1 18:46 home
dr-xr-xr-x. 1 root root 172 Jun 2 09:39 root
dr-xr-xr-x. 1 root root 172 Jun 2 09:39 root-f21
So now I have a snap of f21 root in in root-f21 subvol, and I should be able
to rollback by editing grub.cfg and /etc/fstab to point to root-f21 subvol
instead of root subvol, correct?
Correct. One small problem is the fstab in root-f21/etc/fstab still
has mount option subvol=root. So you'd maybe want to change that or
you get boot failure.
Another problem is a good chance that F21 kernels get removed
(eventually) from the ext4 /boot and then you can't use a Fedora 22
kernel menu entry since root-f21 lib/modules doesn't have those
kernels. So you'll want to make sure you have both /etc/yum.conf and
/etc/dnf/dnf.conf set to preserve more than 3 kernels to make sure
neither one starts deleting kernels you might need.
Of course, then the problem is ext4 /boot can become full which is why
we really need /boot on Btrfs support from grubby. :-P
Only 22 days later...
--
Chris Murphy