Snapshotting for rollback after updates was[ Re: Drawing lessons from fatal SELinux bug #1054350]

Reindl Harald h.reindl at
Sun Jan 26 20:40:52 UTC 2014

Am 26.01.2014 21:30, schrieb Chris Murphy:
> On Jan 26, 2014, at 12:51 PM, Reindl Harald <h.reindl at> wrote:
>> Am 26.01.2014 20:45, schrieb Chris Murphy:
>>>> So ?
>>>> It is only visible if you downgrade which a lot of software do not
>>>> support and explicitly so
>>> The right way to do file format changes is you design the new format. 
>>> And in a minor version update, the application gains the ability to 
>>> read the new file format, but still writes the old file format. 
>>> The major version upgrade of the application is enabled to write the 
>>> new file format, while it can read either old or new formats.
>> please look at the hidden folders in your userhome and /var/lib/
>> to get a picture about what we are talking here
> This sounds like FUD and there's no actual real world example

* i do not know what *may happen* by restore a snapshot
* you do not know what *may* happen by restore a snapshot
* nobody knows


because nobody *can* know what exactly packages, versions are installed
in which combination or which *user specific* data may exist on exactly
the FS which is restored *additionally* to what the system sofware knows

frankly you can have your kwallet or the files your browser stores
passwords you recently created and thought they are safe on exactly
that FS, and they *maybe* saved *between* upgrade, realize a problem
and restore the snapshot

again: *nobody* knows for sure the *complete possible impact* on the
users computer by restore a snapshot because a upgrade should be
rolled back

surely, you can do that, i and many other people won't do this now
nor in the future for good reasons and not knowing *exactly* any
possible impact of a operation is a *damned good* reason

nothing more to say about that topic because

* i *never* won't do that
* i *never* would use LVM
* i *never* use BTRFS
* so my environment even does not support that snapshots

why i won#t use BTRFS/LVM?

because my drives are a Linux RAID10 and i never re-installed my system from
scratch nor would i do that in the future and *because* not everybody is using
a storage even supports snapshots it would be a bad idea to rely on that

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