tar provides following options to handle incremental backup

 –listed-incremental=snapshot file (-g snapshot file)

–incremental (-G)


[root@localhost~]# tar –create –file=archive1.tar listed-incremental=/var/log/usr.snar /usr

 Above command will create archive1.tar as incremental backup of /usr file-system, additional metadata will stored in file/var/log/usr.snar file. If /var/log/usr.snar file not exist it will get created, the created archive will then level 0 backup.

Now suppose for the same example, if /var/log/usr.snar exist. Then above given will check which files get modified and only those files stored in archive, so that will be level 1 backup.

 So the best option is take level 0 (full) backup first as following 

[root@localhost~]# tar –create –file archive1.tar –listed-incremental=/var/log/usr.snar

copy that file 

[root@localhost~]#cp /var/log/usr.snar /var/log/usr.snar-1

Then take incremental backup as follows 

[root@localhost~]#tar –create –file archive2.tar –listed-incremental=/var/log/usr.snar

To extract content from backup we also have to follow same steps which followed at the time of backup. In our example the procedure will be as follows
[root@localhost~]# tar –extract –listed-incremental=/dev/null –file=archive1.tar
Followed by
[root@localhost~]#tar –extract –listed-incremental=/dev/null –file=archive2.tar 

Posted in: Linux.
Last Modified: October 23, 2013

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