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 <options> <destination> <source>
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 <path> <file name> <source>
ex:tar -cvf passwd.tar /etc/passwd
To list the content of tar file
#tar -tvf <path> <file name>ex:tar -tvf passwd.tar
To extract content of file
#tar -xvf <path> <file name>
ex:tar -xvf passwd.tar
To take backup along with zip
#tar -cvzf <path> <file name>
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 <path> <file name>
example :
#tar -xvzf passwd.tar.gz
2) cpio(copy input/output):
Backup using cpio:
#ls <options> | cpio -ov > <file name>
example:ls -l | cpio -ov > sun
To extract:
#cpio -iv <file name>
example:cpio -iv sun
3) dump :
Backup using dump:
#dump -Ouf <device> <file name>example:dump -Ouf /media/<pendrive> sun
To extract:
#restore -f <path>example:restore -f sun
Remote backup:
#rsync -avz <source> -e ssh <destination IP>:<directory>
example:rsync -avz mahesh -e ssh 192.168.1.20:/root/mahesh
#scp -r <source> <destination IP>:<directory>
example:scp -r mahesh 192.168.1.20:/root/mahesh
