[CVALE] Backup/Imaging

[Matt R Hall]

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