Re: Backups


Subject: Re: Backups
captgoodnight@acsalaska.net
Date: Sun Feb 08 2004 - 20:37:44 AKST


On Sunday 08 February 2004 05:58 pm, Bob at Estiminc wrote:
> Here's a backup idea I've been mulling over.
>
> The Strategy:
> 1. Install a mobile rack[1] in my computer (running Linux RH9), and have
> two matching HDD's that I can easily swap out, on a regular schedule. Call
> this drive "Backup", and mount it to the filetree.

Hot swapping.
IDE or SCSI?
Does the controller/modules support hot swapping? IMPORTANT

example-
My hightpoint controller/modules support swap out but not in. I have to shut
down to swap in or else the modules choke the running kernel, reboot,
downtime :(
 

> 2. Install a full, bootable OS (with all settings &configuration matching
> theprimary) on both backups.
Maybe clone the RH9 partitions (partimage or something similar ), Once weekly
to get the exact clone. Though with partimage, the partitions being cloned
need to be umounted, this means downtime for the main Rh9 distro/partitions.
To keep downtime/resources to a minimal ( 1 clone) you could clone drive a to
b, reboot, then b to c with maybe using a different machine. Partimage works
from a bootable CD too (this is a to b).

> 3. Then every night, run a cron job that copies whatever data and config
> files that were changed that day, to "Backup".
Depends on the FILES/DIR/method, rsync? It may be impossible to get an exact
clone without cloning the partitions themselves, again downtime.

> 4. Once a week or so, swap out the backup drives, take one offsite, keep in
> asafe place.
>
smart ;)

> Main question(s):
> 1. If the primary HDD on this machine failed, could I just change the
> BIOS (in Setup) to boot from the 2nd (backup) drive and be up and running
> as if nothing had happened? Or at least be able to stay functional, with a
> minimum of downtime &hassle, giving me time to deal with fixing/replacing
> the primaryproblem?

depending on the mobo ICs, BIOS, bus, controller/module combo, yes. Maybe a
tight fitting partimage will make it more exact. A custom light kernel will
make the job easier all around too, but question below is really unlikely
then.

> 2. If I were to drop one of these backup HDD's into some other machine,
> couldI just as easily boot from it? (In case some other catastrophe
> happened,that totally fried the first machine, e.g. a fire.)
>

Unlikely, different mobo, controllers, bus ect... modules/init/configs and
such would be off. If same machine ect... most likely, maybe. Never done it.
Think maybe though ;) This depends also on the kernel, custom tight fitting
(exact machine) or baggy (maybe at best, i think.)

On some of my servers/workstations I have them do nightly rsync jobs of /home
and weekly full partition clones of total, using IDE to IDE. Others are just
full partimage clones done bi-weekly at best (only a firewall [smoothwall]
and a honeypot [thp] ;) )
Works. I was think of adding a hardlinking sort of a thing to the nightly
/home jobs, hmmm, say 5 times quickly :) Check out the idea of hardlinking
(mirroring method?) too, maybe there's room for it.

Bests,
eddie

ps- hope that makes sense ;)

> If so, here are the perceived benefits I see:
> 1. Cheap. Total cost of hardware is $27 for the mobile rack--or $54 if I
> buy a 2nd one to put in another machine, zero for HDD's (if I use some
> "old" 40GB drives pulled out of other machines that were recently
> upgraded.) This is a lot cheaper than buying &running a backup server.
> 2. Easy. Recovery involves rebooting machine, hitting F2 during bootup,
> changing boot drive setting, and rebooting again. Voila. I'm up &running.
> (Maybe. Depending on answers to above..?)
> 3. Provides more multi-level redundancy than RAID1. Depending on how often
> the 2 backup drives are swapped out, worst case is a loss of 1 day's work,
> and even that would require some cascading failures.
>
> What do people think of this idea? Does it have merit?
>
> --- Links ---
> 1 http://www.buyaib.com/hddmobracwit.html
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