Linux – How to restore a backup from a tgz file in linux

If you have a network connection then just do a ssh pipe.

ssh user@host "cat > file.remote" < file.local

If you need to split the file for media then use split to break it up and cat to fuse it back together.

split -b 1G file.local filexfer
cat filexfer* > file.remote

Note that all this assumes that the remote filesystem is actually capable of storing files that large.

Simply restoring the HDD will not be enough, you're probably will want your boot record too which I hardly believe exists in your backup (am I wrong?, it's better for you if i do!)...

Lest assume you got the server to the point it can boot (i personally prefer creating the additional partition mounted to /boot which will have kernel and initrd with busybox or something similar to allow you basic maintenance tasks). You can also use a live CD of your Linux distribution.

Mount your future root partition somewhere and restore your backup.

tar was created for tapes so it support appending to archive files with same name. If you used this method just untar -xvpf backup.tar -C /mnt if not you'll need to restore "last sunday" backup and applying deferential parts up to needed day.

You should keep in mind that there is a lot of stuff that you should not backup, things like: /proc, /dev, /sys, /media, /mnt (and probably some more which depend on your needs). You'll need to take care of it before creating backup, or it may became severe pain while in restore process!

There is many points that you can easily miss with that backup method for whole server:

• commands used to restore may vary to much depend on real commands you used to backup your data.
• boot record
• kernel image and modules are ok and match each other after restore
• ignore unwanted stuff on backup not restore.
• etc, etc...

Some good points on that exact method can be found on Ubuntu Wiki:BackupYourSystem/TAR. Look for Restoring.

BTW:

• have you ever tried to restore one of your backups?
• have you considered changing your backup strategy?
• have you considered separation of data you need to backup and system settings (there is some good stuff today to manage system configuration so it can be easily resorted with zero pain like puppet or chief, so only thing you should care about is real data)

P.P.S

I recommend reading couple of Jeff Atwood posts about backups http://www.codinghorror.com/blog/2008/01/whats-your-backup-strategy.html and http://www.codinghorror.com/blog/2009/12/international-backup-awareness-day.html