creating
a disaster recovery backup
first you
need to understand how a hard drive and it's partitions relate to your
server installation
When you boot your pc, it checks to see if there is boot information in
the master boot record of the drive. The master boot record tells the
pc hardware to look at (usually, but not always) the first partition on
the drive and try to load the software that it finds (that would be the
operating system). Otherwise, it will skip to the first sector of the
first partition and try looking there. If no boot information is found
in either location, your pc will not start up.
With linux you need
to have at least two partitions. One for the root of your filesystem "/",
and one partition for swap space (virtual memory). I usually create several
partitions when I build a server. This is to seperate key componenets
of my server so something like a log file that has gotten too big will
not fill up the hard drive and crash the server. Instead it would fill
up the partition that contains the log file and stop the log from being
able to grow until the issue is fixed not affecting the server as a whole.
When planning a server installation always keep maximum uptime in mind.
So for my example,
I have a drive that has 8 partitions. See below chart for details.
So enough intro, here
is what needs to be done. All of the partitions need to be backed up.
A boot floppy needs to be created and you need to save a few config files
for reference as to how to put together a server from the pieces of your
backup.
record some
information from the drive you wish to backup
At a console logged in as root issue the following commands and
copy the output of those commands to a text file using "copy and
paste". Save the file for future reference.
get detailed
partition info with fdisk
# fdisk /dev/hda
# p
# q
see output
The above command will enter the fdisk program looking at /dev/hda (drive
#1). Once inside the fdisk program the "p" command prints the
partition map. Then a "q" will quit the fdisk program.
get the contents
of /etc/fstab
# less /etc/fstab
see output
see what partitions
are mounted and where
# mount
see output
similar to
mount but easier to read
# df -h
see output
create a boot
floppy
You will need this to boot a restored backup the first time.
create the
backup
Remove the hard drive from linux box #1. Install it on linux box #2 as
a slave to the primary drive.
Boot up linux box # 2.
create mount
points for the drive you wish to copy
# cd /
# mkdir copy
# cd copy
# mkdir 1 2 5 6 7 8
Notice that 3 and 4 are not in the above command. That is because partition
3 (swap) and 4 (extended) contain no files.
mount the
partitions to be copied
# mount /dev/hdb1 1
# mount /dev/hdb2 2
# mount /dev/hdb5 5
# mount /dev/hdb6 6
# mount /dev/hdb7 7
# mount /dev/hdb8 8
now if you look inside
/copy/1 you should see the contents of partition 1 and so on.
create compressed
archives of the partitions that you just mounted
# cd 1
# tar -czf ../partition1.tgz *
# cd ../2
# tar -czf ../partition2.tgz *
# cd ../5
# tar -czf ../partition5.tgz *
# cd ../6
# tar -czf ../partition6.tgz *
# cd ../7
# tar -czf ../partition7.tgz *
# cd ../8
# tar -czf ../partition8.tgz *
This will create compressed (tar & gzip'd) archives of the corresponding
partitions.
make an image
of the boot floppy that you created
# cat /dev/fd0 > server_boot_floppy.img
now prep for
burning a cd rom of your backup
What you need to do is put the boot floppy image all of the .tgz files
and the screen output copies that you made on a cd. So transfer all of
the files to a machine that you can burn a cd from and burn a copy.
now
see how to restore form the backup you just created
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