196 lines
5.6 KiB
Text
196 lines
5.6 KiB
Text
ccollect - Restoring backups
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============================
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Nico Schottelius <nico-ccollect__@__schottelius.org>
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0.1, for all ccollect version, Initial Version from 2008-07-04
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:Author Initials: NS
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Having backups is half the way to success on a failure.
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Knowing how to restore the systems is the other half.
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Introduction
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------------
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You made your backup and now you want to restore your
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data. If you backuped only parts of a computer and need
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only to restore them, it is pretty easy to achieve.
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Restoring a whole system is a little bit more
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difficult and needs some knowledge of the operating system.
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Restoring parts of a system
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Log into your backupserver. Change into the
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backup directory you want to restore from.
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Do `rsync -av './files/to/be/recovered/' 'sourcehost:/files/to/be/recovered/'.
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Restoring a complete system (general)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Boot the system to be rescued from a media that contains low level tools
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for your OS (like partitioning, formatting) and the necessary tools
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(ssh, tar or rsync).
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Use
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- create the necessary volumes (like partitions, slices, ...)
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Get a live-cd, that ships with
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- rsync / tar
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- ssh (d) -> from backupserver
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- support for the filesystems
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Restoring a complete FreeBSD system
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Get a FreeBSD-live-cd (I used the FreeBSD 7.0 live CD,
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but FreeSBIE (http://www.freesbie.org/),
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Frenzy (http://frenzy.org.ua/en/) or the
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FreeBSD LiveCD (http://livecd.sourceforge.net/)
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may also be helpful. The following way uses the FreeBSD 7.0
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live cd.
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So boot it up, select your language. After that select
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*Custom* then *Partition*. Create the slice like you want
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to have it. Then let the installer write into the MBR,
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select *BootMgr*.
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After that create the necessary labels, select *Label* and
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make sure "Newfs" flag is set to "Y".
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Finally, select *Commit* and choose an installation type
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that must fail, because we want the installer only to write
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the partitions and labels, but not to install anything on it.
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At this point we have created the base for restoring the whole
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system. Move back to the main menu and select *Fixit*, then
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*CDROM/DVD*. This starts a shell on TTY4, which can be reached
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by pressing *ALT+F4*. Then enter the following data:
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--------------------------------------------------------------------------------
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rootdir=/ccollect
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rootdev=/dev/ad0s1a
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backupserver=192.42.23.5
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# create destination directory
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mkdir "$rootdir"
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# mount root; add other mounts if you created more labels
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mount "$rootdev" "$rootdir"
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# find out which network devices exist
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ifconfig
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# create the directory, because dhclient needs it
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mkdir /var/db
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# retrieve an ip address
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dhclient fxp0
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# test connection
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ssh "$backupserver"
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# go back
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backupserver% exit
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--------------------------------------------------------------------------------
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Now we've prepared everything for the real backup. The next problem maybe,
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that we cannot (should not) be able to login as root to the backup server.
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Additionally the system to be restored may not reachable from the backup server,
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because it is behind a firewall or nat.
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Thus I describe a way, that is a little bit more complicated for those, that
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do not have these limitations, but works in both scenarios.
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I just start netcat on the local machine, pipe its output to tar and put
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both into the background. Then I create a ssh tunnel to the backupserver,
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which is then able to connect to my netcat "directly".
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--------------------------------------------------------------------------------
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# user to connect to the backupserver
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myuser=nico
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# our name in the backup
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restorehost=server1
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# the instance to be used
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backup="weekly.20080718-2327.23053"
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# Need to setup lo0 first, the livecd did not do it for me
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ifconfig lo0 127.0.0.1 up
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# change to the destination directory
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cd "$rootdir"
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# start listener
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( nc -l 127.0.0.1 4242 | tar xvf - ) &
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# verify that it runs correctly
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sockstat -4l
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# connect as a normal user to the backupserver
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ssh -R4242:127.0.0.1:4242 "$myuser@$backupserver"
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# become root
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backupserver% su -
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# change to the source directory
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backupserver# cd /home/server/backup/$restorehost/$backup
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# begin the backup
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backup # tar cf - . | nc 127.0.0.1 4242
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# wait until it finishes, press ctrl-c to kill netcat
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# logoff the backupserver
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backupserver# exit
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backupserver% exit
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--------------------------------------------------------------------------------
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Now we are just right next to be finished. Still, we have to take care about
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some things:
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- Do the block devices still have the same names? If not, correct /etc/fstab.
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- Do the network devices still have the same names? If not, correct /etc/rc.conf.
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If everything is fixed, let us finish the restore:
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--------------------------------------------------------------------------------
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# cleanly umount it
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umount "$rootdir"
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# reboot, remove the cd and bootup the restored system
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reboot
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--------------------------------------------------------------------------------
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Restoring a complete Linux system
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Knoppix
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knoppix 2 at boot prompt
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rootdir=/ccollect
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dev=/dev/hda
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rootdev="${dev}1"
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fs=jfs
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tar
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# create the needed partitions
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cfdisk $dev
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mkfs.$fs $rootdev
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mkdir $rootdir
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mount $rootdev $rootdir
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cd $rootdir
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pump
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ifconfig
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# start listener (from now on it is the same as
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( nc -l 127.0.0.1 4242 | tar xvf - ) &
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TO BE DONE
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Future
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------
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I think about automating full system recoveries in the future.
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I think it could be easily done and here are some hints for
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people who would like to implement it.
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