BTRFS/Rollback & Yum Snapshot Plugin

[Jorge Fábregas]

On 01/31/2014 12:29 AM, Chris Murphy wrote:

> FYI note the top level is 257 which is root subvolume, therefore this 
> entry is the same as saying "top level 5 path root/yum_20140130172422"

Indeed.  What a coincidence. The other day I was confused about what
"top level" meant and after searching for:  btrfs "top level is" ...I
found a linux-btrfs' thread where your explanation nailed it.  Not only
that, I've been searching for other btrfs issues and keep bumping into
your replies in that mailing list where you help others.  So, my hat off
to you.  Thanks for your time helping others in the community.


> Another option is to look at snapper. It uses a subvolume at the top 
> level called .snapper that it puts snapshots into. It's in the fedora repo.

Ok, I might check that.  All these years I've been using Clonezilla to
do a "partition image" of my root filesystem before applying major
updates.  I have the ISO stored on my disk and GRUB2 is configured to
boot ("loopback") this image (this is great as I don't need to use a USB
stick or CD anymore).   Of course, using this btrfs snapshot
functionality with yum is by far way better & sophisticated than my
current method.  I wished it were more polished. That is, as soon as yum
snapshots your system, it should create the proper GRUB2 entry (pointing
to your snapshot volume so you can easily rollback) instead of you doing
it manually.

Of course, I'm just testing this on a VM.  My main system still runs
ext4 across the board.  I plan to start using btrfs gradually.  My
nearest plan is to switch my /backup partition (where my backup drive
is) to btrfs.  I plan to rsync my /home over there and then create the
snapshots there (and do some snapshot rotation of course).

> Do you know if these are read only snapshots?
> 
> btrfs sub show /home/yum_20140130172422

They aren't.  I just checked now and could write to them.

Thanks,
Jorge