[nflug] Verifying a cdrom image backup

Mon Dec 15 15:34:43 EST 2008

That sounds even simpler than what I'm trying to do now, but how easy i
it to verify that it worked? I guess I just have to unplug my main drive
and put the backup one in. That's not too tough, but I don't really want
to pull my system apart every time.

I have a removable drive bay I could use that holds my current backup
drive. What I don't know is how to set the machine up so lilo can boot
from the backup drive as an option on its menu.

Joe

SilverBear wrote:
> Well, I agree it's best to keep data separate, and backed up separately.  But a person might also have his OS tweaked "just so." Reinstalling and then dl/installing  all the right packages could be a hassle.
>
> With prices as low as they are these days, a separate backup HDD that can mirror selected partitions, including OSs, is quite practical. It needn't be always mounted --or even physically connected-- just so long as it's convenient to attach to the system when needed.
> Backing up a whole 8GB OS partition with dd from a liveCD usually takes 15-20 minutes or so, if I remember correctly. I have 2GB RAM, so adjust for that. Yes, disk write and bus speeds play a large part in how soon a dd command will complete large amounts of data, but RAM seems to factor in as well.
>
> John
>
>   
>> -----Original Message-----
>> From: cloudlakedreamer at yahoo.com
>> Sent: Sun, 14 Dec 2008 13:34:41 -0800 (PST)
>> To: nflug at nflug.org
>> Subject: Re: [nflug] Verifying a cdrom image backup
>>
>> Who has time to mess with restoring from lots of CD-ROM's ? I backup my
>> data, and then if necessary, I'll just reinstall, then come back and
>> restore my scripts, my email, etc... Just an idea, it might save you a
>> lot of time.
>>
>> Daniel
>>
>>
>> --- On Fri, 12/12/08, Christopher Hawkins <chawkins at bplinux.com> wrote:
>>
>>     
>>> From: Christopher Hawkins <chawkins at bplinux.com>
>>> Subject: Re: [nflug] Verifying a cdrom image backup
>>> To: nflug at nflug.org
>>> Date: Friday, December 12, 2008, 9:37 AM
>>> http://www.mondorescue.org/
>>>
>>> See above - it's an open source package that does
>>> exactly what you describe. I have used it before and I think
>>> there's an option in the menu interface to verify all
>>> data on all cds. Maybe you would be better off with their
>>> software and maybe not, but either way you might just
>>> download their code and see how they do verification.
>>>
>>> Agree with Brad... The only way to know is to actually
>>> restore it and then compare. Maybe restore then rsync -avn
>>> original_dir/* restored_dir/
>>>
>>> The -n option means don't transfer anything, just tell
>>> what would have been transferred. That will give you a file
>>> level comparison that would ignore differences in the
>>> underlying media, filesystem, whatever, and you could run it
>>> even with the restore on another machine or just with the
>>> .iso mounted.
>>>
>>> Chris
>>>
>>> ----- Original Message -----
>>> From: "Joe" <josephj at main.nc.us>
>>> To: nflug at nflug.org
>>> Sent: Friday, December 12, 2008 2:39:30 AM GMT -05:00
>>> US/Canada Eastern
>>> Subject: [nflug] Verifying a cdrom image backup
>>>
>>> I'm making image backups of my system in chunks that
>>> fit on cdroms.
>>>
>>> I created files such as rootu001.iso, rootu002.iso, etc.
>>> using dump with
>>> an unmounted file system.
>>> Then, I used cdrecord to burn a CD which has a file called
>>> rootu001 ...
>>> on it.
>>> Next, I ran md5sum against each and they do not match.
>>> I did this twice (two cdroms).
>>> I did an ls -l of both files and the .iso file is somewhat
>>> larger than
>>> the one on the cdrom.  There were no error messages, etc.
>>> during the
>>> burn (using burnfree which is supported on the drive).  As
>>> far as I
>>> know, the cdrom drive is working fine.
>>>
>>> I just ran a 15 cdrom backup that worked fine, but I
>>> realized afterwards
>>> that since the root file system was mounted, the backup was
>>> probably
>>> useless, so I recreated it using a livecd with the root
>>> unmounted.
>>> That's the one I'm having trouble verifying now.
>>>
>>> Am I doing something wrong?
>>>
>>> How do I verify that what I wrote to the cdrom is identical
>>> to the image
>>> on disk and is completely readable - a reliable/restorable
>>> copy?
>>>
>>> TIA
>>>
>>> Joe
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>>>       
>>
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