Ubuntu System Restore

Mon Oct 31 17:26:02 UTC 2011

Hello Bear Giles
Thanks a lot for your help.
On Mon, Oct 31, 2011 at 2:10 AM, 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.)
>
Ok. A local repository for keeping the packages for being installed
offline, also can I save dpkg packages using dpkg-repack  and then restore
them later using dpkg -i ? The dpkg-repack saves the changes done to the
conffiles the man page says that. But I haven't tried that yet, do you have
any idea about that ?

> 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.
>
Ok. Yes this could be a problem , may be this can be solved using
dpkg-repack for saving the packages .deb files.

>
> 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.
>
Yes I had also confusion regarding that. It would be a lot more difficult
then (in case dpkg-repack also does not recognize the file or the changes
done to that file)  . Then I need to extract the archive and then see for
the changes. Also if some files of a package are corrupted is there any way
of checking 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.
>
Ok thanks for this idea.

>
> 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
>>
>
>

-- 
Thanks and Regards ,
Gaurav
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.ubuntu.com/archives/ubuntu-devel-discuss/attachments/20111031/2c0d4ca2/attachment.html>