Re: lenny backups and recovery
On 20100121_095411, Robert Brockway wrote:
> On Fri, 15 Jan 2010, Paul E Condon wrote:
>
> >Contrary to tldp advice, I think it is unnecessary to make backups
> >of /bin or /sbin. These files are readily available from you favorite
>
> I'm very much a fan of backing up the entire system (with limited
> exceptions, such as an area set aside for the storage of downloads,
> that is not backed up.
>
> The problem is that unless you restore to the _same_ binary you can't
> guarantee the same behaviour. This is essential in the case of
> server backups where there is little tolerance for behavioural
> changes but still applies to desktop systems.
>
> A similar argument applies to the complete setup of the system.
> Despite the best change management, small and non-obvious changes can
> occur in a system. If you reinstall from the repo and restore the
> config from /etc you may still be missing something (eg, a symlink)
> and find an app is broken when it was previously working. Backing up
> the entire state of the system means that when you do a DR you get
> back a known working copy of the system, since it was working before.
>
> I'd consider having to reinstall from original media a failure of the
> DR system.
>
> When I first started with Linux the system (binaries and config) took
> up about 80% of the disk. Now it takes up less than 2%, so backing up
> the system components hardly adds any pressure to the backup system.
> It also allows for a much faster recovery following a DR.
>
> Also, important data has a way of hiding in more places on the disk
> that you think it will. If you start excluding parts of your system
> from the backups you increase the liklihood of missing something
> important in the backups.
>
> This is covered in more detail in my backup talk notes (which I did
> mention earlier in the thread):
>
> http://www.timetraveller.org/talks/backup_talk.pdf
>
> >Debian repository, and if your system has crashed in some serious
> >way, you would be well advised to download again, once you think you
> >have resolved the issue that caused the crash. Think about it ---
> >if you have to restore one of these, something really bad has happened
> >and you can't be sure that something -else- bad hasn't also happened -
> >but you haven't noticed it - yet.
>
> That's where testing of the backup system comes in. You never know
> that DR will work unless you test it.
>
> Cheers,
>
> Rob
Rob,
I think we have different working conditions in mind. And, anyway, my
comments were directed toward the system given in the tldp.org
document. I see your document as advice to the systems people in a
small business. It is good advice, and I commend you for it.
I imagined OP to be somewhat of a newbie and slightly overwhelmed, not
a systems person in a small business. I now think OP is not so much a
newbie, and is quite capable of ignoring advice that doesn't address
his issues, but that was the context for what I wrote.
The tldp.org document is entitled
"Linux-Complete-Backup-and-Recovery-HOWTO". One of the first things I
noticed about it is that it assumes that you already -have- a daily
backup system in place, and then it makes no attempt to integrate what
it is presenting with that system, or even suggest a review of the
design of that system. And yet it claims to be 'complete'.
I think we can agree, it is not complete.
Peace.
--
Paul E Condon
pecondon@mesanetworks.net
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