Linux system Backup and recovery

Transferred from: http://blog.csdn.net/sunnylgz/article/details/8055315

Before using Ubuntu, I believe many people have experienced the use of Windows systems. If you've backed up your Windows system, you must remember that you first need to find a backup tool (usually private software) and then restart your computer to the software environment provided by the Backup utility where you can back up or restore your Windows system. Norton Ghost is a backup tool that is often used when backing up Windows systems.

When backing up the Windows system, you might have thought that I could put the entire C-drive in a zip file. This is not possible under Windows because there are many files in Windows that are not allowed to be copied or overwritten when they run, so you need specialized backup tools for special processing of Windows systems.

Unlike backup windows, if you are backing up your Ubuntu system (or any other Linux system), you no longer need backup tools like Ghost. In fact, Ghost's backup tools are poorly supported for Linux file systems, for example, some ghost versions can only fully support the Ext2 file system, and if you use it to back up the Ext3 file system, you may lose some valuable data.

1. Backup system

How do I back up my Ubuntu system? It's simple, just like you're backing up or compressing something else, using tar. Unlike Windows, Linux does not restrict root access to anything, you can throw everything on the partition into a tar file!

First become the root user:
$ sudo su

Then go to the root of the filesystem (of course, if you don't want to back up the entire file system, you can also go to the directory you want to back up, including the remote directory or the directory on your hard drive):
# CD/

Here is the complete command I used to back up the system:
# tar Cvpzf backup.tgz–exclude=/proc–exclude=/lost+found–exclude=/backup.tgz–exclude=/mnt–exclude=/sys/

Let's take a brief look at this command:

"Tar" is, of course, the program we use to back up our systems.

"CVPFZ" is the tar option, meaning "Create profile", "Keep permissions" (keep everything original), "Use gzip to reduce file size".

"Backup.gz" is the file name of the archive file we are going to get.

"/" is the directory we want to back up, here is the entire file system.

Directories that must be excluded from the backup are given between the file name "backup.gz" and the Directory Name "/" to be backed up. Some directories are useless, such as "/proc", "/lost+ found", "/sys". Of course, the "backup.gz" file itself must be excluded, otherwise you may get some out of the ordinary results. If you do not exclude "/mnt", other partitions that are mounted on "/mnt" will also be backed up. Also need to confirm that "/media" does not mount anything (such as CD-ROM, mobile hard disk), if there is a mount thing, must be "/media" also excluded.

One might suggest that you exclude the "/dev" directory, but I don't think it's a good idea to do this, but it's not discussed here.

Before you execute the backup command, confirm that the command you typed is what you want. The backup command may take a short time to execute.

After the backup is complete, a file named "Backup.tgz" will be generated at the root of the file system, and it may be very large in size. Now you can burn it to a DVD or put it where you think it's safe.

At the end of the backup command you may see a hint: ' Tar:error exit delayed from previous errors ', in most cases you can ignore it.

You can also use BZIP2 to compress files, BZIP2 is higher than gzip compression rate, but slower. If the compression ratio is important to you, then you should use BZIP2, "J" instead of "Z" in the command, and give the file a correct extension "bz2". The complete command is as follows:
# tar CVPJF backup.tar.bz2–exclude=/proc–exclude=/lost+found–exclude=/backup.tar.bz2–exclude=/mnt–exclude=/sys/

2. Recovery system

Be careful when you are working on a recovery system! If you don't know what you're doing, you may lose important data, so be careful!

Then the above example. Switch to the root user and copy the file "Backup.tgz" to the root directory of the partition.

One of the great things about Linux is that you can restore your system in a running system without having to use BOOT-CD to boot specifically. Of course, if your system has been hung up and cannot be started, you can use the live CD to start, the effect is the same. You can also kill all the files in the Linux system with one command, but I'm not going to give this command here!

Use the following command to restore the system:
# tar Xvpfz backup.tgz-c/

If your profile is compressed using BZIP2, you should use:
# tar XVPFJ backup.tar.bz2-c/

Note: The above command overwrites all files on the partition with the files in the archive file.

Before executing the RESTORE command, please confirm that the command you typed is what you want, and it may take a short time to execute the restore command.

At the end of the restore command, your work is not finished, and don't forget to recreate the directories that were excluded from the backup:
# mkdir Proc
# mkdir Lost+found
# mkdir MNT
# mkdir SYS
Wait a minute

When you restart your computer, you'll find everything back to what you did when you created your backup!

Linux system Backup and recovery