[CVALE] Backup/Imaging

[Dennis Baker]

First,  RAID should never be confused for backup.  They serve two similar
but different purposes.  RAID is for fault tolerance.  In other words if
your hardware fails your system doesn't go down.  Backups are for disaster
recovery.  One such disaster Matt mentioned is operator headspace,  in other
words you the operater inadvertently screw something up (none of us have
ever done that have we?).  Another would be outside attack,  or complete
system destruction (what if there is a fire and your computer is
destroyed?).  RAID does not mitigate the damage from any of these
scenarios.  Don't fool yourself into a false sense of security believing
that RAID will save your bacon.

That said... Matt what are you backing up that is that huge?  Maybe you
should triage your data.  Personally about the only thing I back up on a
regular basis are personal documents (resume,  financial stuff, etc), family
photos, and my web site which I have quite a bit of time/ energy into.
Beyond that,  games,  movies, MP3s, etc are never backed up since they are
replacable.  Almost all of that stuff for me fits on a single DVD.

To back up as much what you are talking about you need something much more
sophisticated,  either an expensive tape system or tons of DVDs.... ??

How about partnering with someone else or even two other people.  Build up a
small backup system with enough drive space to store your backup and rsync
your system to it (do this locally the first time).  Then install the system
at another location and do a weekly rsync to the backup system.  If you are
truly paranoid you can have two backup systems in two locations.

The problem with this solution is that you don't have any permanent
storage.

-- Dennis


On 9/25/06, Matt R Hall <mhall at mhcomputing.net> wrote:
>
> On 9/25/06, Pandora <cvale at synx.dyndns.org> wrote:
> > Another backup possibility is RAID.  If you're going to go out and
> purchase all those backup hard disks, RAID is a system for automatically
> backing stuff up to them. It's got different levels, but I think most people
> use RAID 1, which is just automatic disk mirroring (also speeds things up
> because you've got two disks working for you at once!).  Sometimes people
> use RAID 5 because it's more efficient in terms of disk usage, more than
> plain old redundant copies that is, but it's also somewhat processor
> intensive and hard on the disk. Depends what you're doing with it really.  I
> like RAID 5 because you can plug 5 disks all into one virtual disk 4/5ths
> their total size, and if any single disk drive fails, you just pull it out,
> and put a new one in, and everything just works.  RAID 1 is like that too,
> except you only get 1/2 of the sum of the size of all your disks (or 1/3rd
> if you back everything up 3 times, or whatever).
>
> As you know I don't always agree with your views but in this case, I
> definitely agree with you 100%. I just starting using Linux MD RAID 5
> on a 1TB data array and a 300GB boot array a few months ago and it's
> seriously the greatest thing since sliced bread.
>
> However I should mention a couple of caveats for the safety of any new
> users lurking on the list: RAID does not protect against improper use
> of mv, rm, chmod, chgrp, and chown. So if you accidentally screw up a
> command there's not much you can do, especially with rm.
>
> The other thing is that you can have certain rare but disastrous
> failures, like let's say a bad power supply, which fry all the drives
> in the box.
>
> So now you see that the problem I have in my environment that I still
> haven't solved is, few things are more frustrating than having to back
> up that much data. I'd like to be able to use Ultrium tapes or
> something but I can't find any afforable way to do this. Ultrium tape
> heads cost thousands. I have several brand new U2 SCSI DAT 20GB drives
> I got from a friend but it would take a huge number of tapes and a
> huge amount of time to go this route.
>
> Is there anybody on list that has some good advice about reasonable
> methods for backing up big arrays? Should I hold out a few months
> until the BluRay optical drives get more affordable and support gets
> written into cdrecord or what else is there to try?
>
> Thanks,
> Matt
>
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>



-- 
Dennis Da-Ogre http://ogrehut.com
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