Adventurous yet Safety-Minded

[Jon Masters]

On Wed, 2010-03-10 at 18:22 +0530, Rahul Sundaram wrote:
> On 03/10/2010 05:36 PM, Steven I Usdansky wrote:
> > Instead of worrying about the occasional brokenness caused by an update to a stable release, how about focusing on a mechanism to easily recover from it? As long as the update hasn't corrupted any critical files, my non-optimal solution is to head over to koji, grab the last version of the broken package set that worked for me, and install. If yum could be persuaded to stash the required deltas locally, and downgrade using those local deltas upon request, I'd be a very happy camper.
> >   
> 
> One feature which can help
> 
> http://fedoraproject.org/wiki/Features/SystemRollbackWithBtrfs

That might be very useful for OLPC users, etc. But (and I mean this with
no disrespect to anyone else) I am not going to want to use it seriously
when it means rolling back everything that changed since installing
updates (sure, if the update is a kernel update and you literally
rebooted the second the update happened, doing nothing else - but most
updates don't bite me until I try to use some app later). I might use
something like this on a specific device, or in a specific context
(netbook with most storage online, embedded device, etc.) but not on a
server or desktop system running Fedora, even with copious additional
filesystems for /home, /whatever. I know the snapshots preserve data,
but I also know that fiddling around to see what files you need to move
around after a rollback makes this fiddly enough to not want to do it.

A better solution would be to be able to rollback individual files or
groups of files to earlier versions, like package management (or like
really treating your filesystem as some kind of git branch), but at a
different level. I'm not a btrfs expert but since it is copy on write,
one would assume that this is also technically possible - rolling back
specific files to earlier revisions if those are available, and having a
means to tag specific older versions of files other than being in a
subvol so that they will not be reclaimed and are kept on the disk. And
I would love to hear some more about whether this is possible/doable.

So anyway, I don't consider whole disk rollback a serious, and generic
solution for handling botched Fedora updates.

Jon.