[K12OSN] Some Back-Up Questions

[Paul Davison]

The question of backup strategies comes up often on this group.  I 
believe the reason for this is that there is such diversity in the 
various setups.

I am going to make an assumption here that a daily backup of your 
critical files will cover your needs, and that you are not terribly 
interested in having the ability to 'roll back' by days, weeks or 
months. I will also assume that you will be available to retrieve the 
backups if required and that you have the essential knowledge to rebuild 
a server and add in the appropriate config files from the backups in a 
disaster scenario.

In this simplified case, I would put forth the following answers to your 
particular situation.

Richard K. Ingalls wrote:

> What open-source solutions are there for this scenario?

I would use rsync and cron to complete the backups.  These are very 
commonly installed by default on all flavours of Linux.
> 
> I have a few K12LTSP classroom servers (NFS mount /home from one of 
> them) and a web/email server and a proxy server, as well as four 
> administrators' PCs that I'd like to back up regularly.  I'd like to 
> build a back-up server to handle all of these backups...

> 1. Do I need two large capacity IDE hard drives and mirror them (for the 
> server)?  If so, software mirroring or hardware?
> 
I would use the large capacity drives and mirror them.  If budget 
allowed, I would use hardware, if not, I would use software. If budget 
was really tight, I would not fret too much over using a single drive 
since the chance of the single drive dying at the same time as one of 
the other systems is quite remote.

> 2. Do I need to backup entire hard drives or just the important portions?
I would backup the /root /home /etc and critical files from /var (like 
mail spool, web pages etc).

> 
> 3. How can I also backup Windows systems onto this server?  (At this 
> point, I'm thinking of using WinSCP2 to manually copy directories onto 
> the server).

I would grab a copy of the rsync package for windows. I use this all the 
time.  Create a batch script that will connect from the windows machine 
to the rsync server. Run the script using  scheduled tasks (or using 
'at' on NT4 machines). The only limitation I have found to rsync is if 
you are transferring single files that are larger than 2Gb. This is true 
of many other types of backup as well.  I don't think 32 bit linux can 
support single files over 2Gb anyway. (anyone have a workaround?)

There is a prebuilt binary in zip format here:
http://optics.ph.unimelb.edu.au/help/rsync/binaries/

For the more adventurous you can go to www.cygwin.com and install cygwin 
and rsync from their site onto the win43 machines.

The beauty of this system is that only updated files are transfered to 
the backup host. Once the initial copy is done, the actual load on the 
network drops off substantially, as does the amount of work the backup 
drives are doing.

A simple add on to this would be a cd-rw drive or a dvd burner, which 
you could use to make a weekly snapshot to take offsite with you.


Hope that helps
Paul Davison