Backup & Recovery Concept on RHEL / CentOS 5.X&6.X

Backup:-

                 

                 Data Backup is the physical copying of data files to a removable  storage device that allows the data to be stored in another location.  When needed, an individual data file or an entire set of data files,  can be restored to a computer system.

USERS OF  BACKUP & RECOVERY:

    1)To copy data to alternate media 

    2)To prevent data loss 

     

     Note: Only administrators can backup the data

Types of data:

      I)System generated data

      II)User generated data

Types of backup:

1)Full backup

      2)Incremental backup

      3)Differential backup

 1)Full backup :   complete backup of entire system

2)Incremental backup:  It includes all files that were changed since last backup. It always smaller than differential backup.

3)Differential backup:  It includes all the files that were changed since last full backup. As time increases since the last full backup the size of differential backup increases.

Commands for backup:

     1)tar (tape archieve)

     2)cpio (copy input/output)

     3)dump

1) tar:

#tar

Note:destination must be in .tar extension

options:

-c=create

-v=verbose

-f=file

-t=table of content

-x=extract to

-w=interactive

-z=zip

To take backup

#tar -cvf

ex:tar -cvf passwd.tar /etc/passwd 

To list the content of tar file

#tar -tvf

ex:tar -tvf passwd.tar 

To extract content of file

#tar -xvf

ex:tar -xvf passwd.tar

To take backup along with zip

#tar -cvzf

Note:file name must be with an extension of .tar.gz

example : #tar -cvzf passwd.tar.gz /etc/passwd

To extract zip file

#tar -xvzf

example : #tar -xvzf passwd.tar.gz

2) cpio(copy input/output):

Backup using cpio:

#ls | cpio -ov >

example:ls -l | cpio -ov > sun

To extract:

#cpio -iv

example:cpio -iv sun

3) dump  : 

Backup using dump:

#dump -Ouf

example:dump -Ouf /media/ sun

To extract:

#restore -f

example:restore -f sun

Remote backup:

#rsync -avz -e ssh :

example:rsync -avz mahesh -e ssh 192.168.1.20:/root/mahesh

#scp -r :

example:scp -r mahesh  192.168.1.20:/root/mahesh