Re: Backup requirement
On Wed, Apr 30, 2008 at 10:55:04PM +0530, Masatran, R. Deepak wrote:
> Old laptop, for personal use, running Debian Etch. I intend to backup every
> month to DVD via my external DVD writer, and to leave copies with friends.
>
> I want encryption. I use LUKS, but only for my home partition.
Then you're giving away all the jucy bits from /etc/ like passwd and
shadow
>
> My hard drive is 80 giga-bytes big. My partitions are home, root, alternate
> root, a data partition, and a Windows NTFS that I have not used in years :-)
>
> Current solution is to "cp --archive" the home partition into an external
> hard drive.
>
> I use GenISOImage and Wodim to burn my data CDs. Also, I prefer CPIO to Tar,
> and command-line to GUI.
>
> I am looking at Mondo <http://www.mondorescue.net/>, etc. Kindly give
> suggestions.
I've never used Mondo. I tried once only to find that the mondo kernel
couldn't boot my machine. I figure that if I found a machine it
wouldn't boot that easily, then my luck would be that the bare-metal I
ended up with after a disaster wouldn't boot either.
Since I run old hardware and like to play around with functionality,
I've done various installs over the years and haven't lost anything so I
must be good at bare metal recovery even without mondo.
Here's what I do:
I have a script on each box that backs-up what is required for that box.
I then have a second script on my main box that does an rsync jitterbug
to get copies of important stuff moved around to other boxes.
Ultimatley, very important stuff (the stuff I would want to have if the
house burned down) goes onto optical media and into the bank's safety
deposit box, and as much data as I can goes onto a 4 GB USB stick which
is set up also as an Etch install USB stick with netinst.iso on it.
This way, if I just want to read data, its on the stick, however, I can
plug that USB stick into bare metal, run an install and get back to
where I was within a day.
It all comes down to how tolerant you are of downtime. If you can't
afford any, then you need some fail-over server setup to a remote site
around the world (or on Mars: New business venture: send a datacentre to
mars with enough redundancy and tape libraries to be great off-site
backup).
If your downtime tolerance is a bit more down-to-earth and you can
tolerate the delay while you get new hardware (or fix what you have),
then a standard backup method is fine.
Here's what you need:
Install set for current hardware and for future hardware. If you run
Etch you may want to have a sid set known (tested) to work in case you
need to install on new hardware. Debian's install has a helpful
rescue mode.
plain-text info for your ISP connectivity.
/etc
/boot/grub/menu.list
output of dpkg --get-selections for a list of __all__ installed
packages.
output of aptitude search '~i!~M' for a list of all installed packages
which are manually (not automatically) installed; the ones you chose.
A copy of the partition table for your drives. I think the command is
fdisk -s. See the man page for the option that gives you a printout
suitable for use as input to fdisk which will allow you to fix a busted
partition table to exactly what it was before.
A second copy of the partition table in easy-to-read format incase you
need to partition a new drive in roughly the same way.
If you use LVM, then a pv,vg,lv display.
Finally you need all your data; /home, any other data directories.
I use tar, pipe it through gzip -9 (best) and pipe it through split (to
fit media if necessary.
Any data that goes to removeable media where security is an issue
(remember that a backup gives whoever holds the backup effective root
access to the whole data set), I pipe the archives through openssl's enc
so that they are incrypted separatly (saves any difficuties with LUKS).
It also is portable in that openssl has binaries on most OS's; I don't
need a linux box to access the archives, just one that can handle an
encrypted openssl archive.
Now that you have a backup set, see how big it is. What media size do
you need? What environment limits do you have (heat, humidity) or
longevity requirements: CDs aren't as long-lasting as 1/2" linear tape
(DLT/LTO). Will the drives for that media be available? If this is
only in case data is lost, then this is less of an issue; presumably if
you backup to CD and need it tomorrow on new hardware, a new CD drive
will read it. However, if you backup on the second-last DLT-I drive
around, you would want to store the last DLT-I (or a DLT-II) drive with
the backups.
Now consider where you want to store your backups, how often to do them,
etc. Some of this comes down to convenience. Any data that you cannot
stand to lose in the event of a disaster in the next day should go
off-site in under a day, for example. Small business may, for example,
take the previous night's backup tape to an employee's home or to a bank
nearby on a daily or weekly basis. This part of the decision making is
very situation-specific.
I hope this gets you started in the right direction.
Doug.
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