Ubuntu System Restore

Gaurav Saxena grvsaxena419 at gmail.com
Mon Oct 31 17:32:19 UTC 2011


Hello John,

On Mon, Oct 31, 2011 at 2:27 AM, John Moser <john.r.moser at gmail.com> wrote:

> The simple way to create a restore point system ...
>
> ... is to mount / as an overlay FS, which you periodically merge (to
> remove prior restore points), condense into a squashfs (to take a
> point backup), or wipe (to restore to backup).  This of course means
> /home should be its own partition.
>
I think this is the idea used by nexenta by mounting / on a ZFS partition,
Can a similar approach used for ubuntu ? But that needs / to be mounted on
a brtfs filesystem, Does that need a thorough reinstall of the system ?
This approach along with package saved state can help to create a break
free upgrade mechanism as is done in nexenta currently.

>
> On Sun, Oct 30, 2011 at 4:40 PM, Bear Giles <bgiles at coyotesong.com> wrote:
> > You need to either have a local repository or download from the internet
> > again. I've used 'apt-mirror' in the past to maintain a local cache but
> that
> > was when I was building local systems with a minimal Debian installer. I
> > don't even know if the standard Ubuntu installer can load off a local
> cache.
> > (I guess the process is to do the install "without updates", change your
> > sources.list files, then upgrade from the cache.)
> >
> > It's also worth remembering that the specific versions of your packages
> may
> > not be available when you need to restore your system. This is usually a
> > good thing since more recent versions have a shot at preventing whatever
> > caused you to lose your system in the first place (e.g., closing
> > vulnerabilities) but some people may need to restore the system exactly.
> > On checksums - I checked my system and almost none of the conffiles have
> > checksums. (In fact that may be against packaging standards - I would
> have
> > to check.) That's a bummer since it means that there's no easy way of
> seeing
> > what's changed unless you peek into the .deb file. There are some deb
> tools
> > that can do this but since I can do it programmatically I usually just
> did
> > that.
> > The 'monster diff' is just a comment on the number of files involved.
> What I
> > actually did create two lists, one generated by walking the filesystem
> and
> > the other generated by concatenating all of the *.files and *.md5sums
> > metadata and then comparing them. I did this programmatically but you
> could
> > also create actual files, sort them, and then run a diff on them. IIRC I
> > typically had over 70k files.
> > On Fri, Oct 28, 2011 at 3:33 AM, Gaurav Saxena <grvsaxena419 at gmail.com>
> > wrote:
> >>
> >> Hello all
> >>
> >> On Fri, Oct 7, 2011 at 4:45 AM, Bear Giles <bgiles at coyotesong.com>
> wrote:
> >>>
> >>> I've written a few prototypes and this comes down to four issues. Some
> of
> >>> the details below are debian/ubuntu-specific but the same concepts will
> >>> apply to redhat.
> >>>
> >>> 1. User data (/home) must be backed up explicitly. (ditto server data
> on
> >>> servers).
> >>> 2. Packages should NOT be backed up. All you need is the package name
> and
> >>> version. Reinstall from .deb and .rpm if necessary since this way
> you're
> >>> sure that you never restore compromised files.
> >>
> >> But it might be possible that the package files are not available on the
> >> system. That means for all the packages installed the .deb files need
> to be
> >> downloaded from the internet for restore purpose ?
> >>>
> >>> 3. Configuration data (/etc) must be backed up explicitly. This is
> tricky
> >>> because backing up the entire directory will cause its own problems.
> Worse,
> >>> some applications keep their configuration files elsewhere. The best
> >>> solution I've found is to scan the package metadata to identify
> >>> configuration files and to only save those with a different checksum
> than
> >>> the standard file.
> >>
> >> Ok. Nice idea indeed , but is there checksum associated with the files
> in
> >> the package ? Or that can be calculated at the time of restore ? What
> you
> >> say ?
> >>
> >>>
> >>> 4. Local files. Ideally everyone would keep these files under
> /usr/local
> >>> and /opt but that's rarely the case. The best solution I've found is
> to scan
> >>> the debian package metadata and do a monster diff between what's on the
> >>> filesystem under /bin, /sbin, /usr and (chunks of) /var with what's in
> the
> >>> metadata.
> >>
> >> Could you suggest me some way of scanning the debian package metadata
> >> without actually downloading the packages? and how to this monster diff
> ?
> >>>
> >>> It's worth noting that the last item isn't that hard if you have a
> strict
> >>> security policy that everything under those directories MUST be in a
> >>> package. It's deleted without a second thought if it's not. You can
> still do
> >>> everything you could before, you just need to create a local package
> for it.
> >>> So what do you do with this? The best solution, which I haven't
> >>> implemented yet, is to handle #2 and #3 with autogenerated packages.
> You set
> >>> up one or more local packages that will install the right software and
> then
> >>> overwrite the configuration files. You can fit everything, including
> >>> original package archive, on a single DVD.
> >>
> >> Could you please tell some detail about autogenerated packages ? Like if
> >> we have a list of packages installed on the system, We need to reinstall
> >> those all softwares  and remove those which are installed after the
> restore
> >> point?
> >>>
> >>> BTW Debian has a C++ interface to the package metadata. I've never used
> >>> it - I find it easier to just scan the metadata directory myself.
> There's
> >>> also hooks that will allow your application to be called at each step
> during
> >>> a package installation or removal. You could, in theory, keep your
> snapshots
> >>> current to the last minute that way.
> >>
> >> So whenever a package is installed or removed I will update my backup
> >> according to that ? By reading package metadata determine which files
> are
> >> changed by that package and update those files in the backup ?
> >>>
> >>> On Fri, Sep 30, 2011 at 12:01 AM, Gaurav Saxena <
> grvsaxena419 at gmail.com>
> >>> wrote:
> >>>>
> >>>> Hello Aaron
> >>>> Thanks a lot for your quick reply.
> >>>>
> >>>> On Fri, Sep 30, 2011 at 10:03 AM, Aaron C. de Bruyn <
> aaron at heyaaron.com>
> >>>> wrote:
> >>>>>
> >>>>> In Windows, the ability to snapshot is built into the filesystem.
> >>>>> In Linux, you must be running a filesystem that supports snapshots.
>  I
> >>>>> know LVM supports snapshotting and I believe BRTFS has support, but
> >>>>> other than that I'm not sure.
> >>>>>
> >>>> Yes I read the logic behind windows system restore. But I think we can
> >>>> take some other approach for this, that will be better as all users
> won't be
> >>>> able to spare an extra partition formatted brtfs.
> >>>>
> >>>>>
> >>>>> Basically, your program would have to check the file system that is
> >>>>> used on the computer (remember Linux can have many types of file
> >>>>> systems mounted at the same time), then (in the case of LVM) make
> sure
> >>>>> there's enough free space to snapshot, and finally take the snapshot.
> >>>>>
> >>>> Ok. Do I have to snapshot the whole system partition / important
> system
> >>>> files to the brtfs partition ?
> >>>>
> >>>>>
> >>>>> When the snapshots start filling up, you would either need to delete
> >>>>> them or detect the low space and resize them.
> >>>>>
> >>>>> In my personal opinion, snapshotting in Linux is currently a pain in
> >>>>> the rear.  It sounds like BTRFS could change that, but it's still a
> >>>>> ways off.
> >>>>>
> >>>> Ok.  I will try another approach that will be better as suggested by
> >>>> people here.
> >>>>
> >>>>>
> >>>>> -A
> >>>>>
> >>>>> On Thu, Sep 29, 2011 at 21:00, Gaurav Saxena <grvsaxena419 at gmail.com
> >
> >>>>> wrote:
> >>>>> > Hello all,
> >>>>> > I want to write a windows system restore like program for ubuntu ,
> >>>>> > which
> >>>>> > will have options for creating restore points for the system and
> then
> >>>>> > restoring it back to that point. Also I will as an extension
> provide
> >>>>> > support
> >>>>> > for older version of a file as is in windows currently. I need your
> >>>>> > help to
> >>>>> > find how to start with this in ubuntu. I know that I have to
> snapshot
> >>>>> > the
> >>>>> > system when creating a restore point and then restore it. I need
> some
> >>>>> > starting pointers so that I can start doing this work. Also if this
> >>>>> > has
> >>>>> > already been done please inform me. I got this idea from
> >>>>> >  https://wiki.ubuntu.com/SystemRestore.
> >>>>> > --
> >>>>> > Thanks and Regards ,
> >>>>> > Gaurav
> >>>>> >
> >>>>> > --
> >>>>> > Ubuntu-devel-discuss mailing list
> >>>>> > Ubuntu-devel-discuss at lists.ubuntu.com
> >>>>> > Modify settings or unsubscribe at:
> >>>>> > https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
> >>>>> >
> >>>>> >
> >>>>
> >>>>
> >>>>
> >>>> --
> >>>> Thanks and Regards ,
> >>>> Gaurav
> >>>>
> >>>>
> >>>>
> >>>> --
> >>>> Thanks and Regards ,
> >>>> Gaurav
> >>>>
> >>>> --
> >>>> Ubuntu-devel-discuss mailing list
> >>>> Ubuntu-devel-discuss at lists.ubuntu.com
> >>>> Modify settings or unsubscribe at:
> >>>> https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
> >>>>
> >>>
> >>
> >>
> >>
> >> --
> >> Thanks and Regards ,
> >> Gaurav
> >
> >
> > --
> > Ubuntu-devel-discuss mailing list
> > Ubuntu-devel-discuss at lists.ubuntu.com
> > Modify settings or unsubscribe at:
> > https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
> >
> >
>



-- 
Thanks and Regards ,
Gaurav
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