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Old 06-22-2012, 07:42 AM
 
Default 'yum update' rollback or .. ?

Hello,

we have several physical servers (CentOS 5.*) with rather critical applications where (because of stability)
we don't do regularly 'yum update'. In virtualized environemnts (under Vmware)
we do a snapshot, then 'yum update', reboot and if something is wrong we rollback the snapshot.
On physical servers we cannot do that. I have read about rollback option of rpm but not sure if
this is reliable solution. What is your best practise regarding "rollbacking" 'yum update' on
physical servers ?


Regards
Przemyslaw Bak (przemol)


















































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Old 06-22-2012, 11:06 AM
Theo Band
 
Default 'yum update' rollback or .. ?

On 06/22/2012 09:42 AM, przemolicc@poczta.fm wrote:
> Hello,
>
> we have several physical servers (CentOS 5.*) with rather critical applications where (because of stability)
> we don't do regularly 'yum update'. In virtualized environemnts (under Vmware)
> we do a snapshot, then 'yum update', reboot and if something is wrong we rollback the snapshot.
> On physical servers we cannot do that. I have read about rollback option of rpm but not sure if
> this is reliable solution. What is your best practise regarding "rollbacking" 'yum update' on
> physical servers ?
>
One solution would be to use lvm snapshots. Create a snapshot of the
root volume (lvcreate -s VolGroup00/LogVol00 -n rootsnapshot -L 10G), do
an update and see if it works. If not, boot into rescue mode and copy
the content from the snapshot back to the original.
Make sure the snapshot gets the same size as the original volume. This
is important if you want to copy back all the data.

Theo
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Old 06-22-2012, 11:58 AM
Nikolaos Milas
 
Default 'yum update' rollback or .. ?

On 22/6/2012 2:06 μμ, Theo Band wrote:

> What is your best practise regarding "rollbacking" 'yum update' on
> physical servers ?
>

Assuming that you have problems due to a particular newly-installed
package, you can downgrade:

rpm -Uvh --oldpackage package-2.4.0-1.el5.x86_64.rpm

or:

yum downgrade package (if it is in the repo)

Since problems are usually introduced by a particular package (and not
by all), this might be enough in most cases.

Note, however, that dependencies are not resolved automatically with the
above commands, so they must be handled manually.

Another, more complete solution, of course, would be to have a full
system backup (regardless whether the system is physical or virtual) and
in case things go wrong, restore from backup (always a bit risky, I know
- it makes you feel uneasy). We use mondorescue without problems (see:
http://www.mondorescue.org/). I have been able to even use the backup to
restore a KVM guest (using LVM) under VMware (you may see
http://mondorescue-mailing-list.679749.n3.nabble.com/Mondo-devel-Restore-from-within-a-new-host-without-boot-td2251272.html).

Or - if feasible - you can attempt to virtualize your physical server,
either using mondorescue or VMware converter (or other commercial tools)
and be ready to use the virtual machine instead.

I am interested on other solutions too, so your thread is interesting!

Nick
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Old 06-22-2012, 12:16 PM
Theo Band
 
Default 'yum update' rollback or .. ?

On 06/22/2012 01:58 PM, Nikolaos Milas wrote:
> I am interested on other solutions too, so your thread is interesting!
dump

Assuming some form of ext[n] filesystem is being used. It has the
advantage that is also works with incremental backups. You can dump the
root file system and perhaps also the /boot filesystem.
Instead of the root filesystem, I dump a snaphost that is created each
evening. The snapshot has a frozen filesystem. So databases (mysql)
should just be consistent. If you want to be 100% sure, stop the
database, make a snapshot and start the database again. This is done
within one second, so hardly any impact on the live server.
Disadvantage of this method is that you still need the have a partition
table if you need to fully restore. And LVM and boot sector need to be
recreated. In case of disaster recovery you need this documented
properly (try it out at least once).
Advantage is that you can have daily system backups automatically created.

Theo
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