BACKUP AND RESTORE


BACKUP AND RESTORE

In this chapter we can do following things using backup and restore commands

  1. backup
  2. restore
  3. rootvg backup
  4. restore rootvg backup
  5. non rootvg backup(other than rootvg)
  6. restore non rootvg backup(other than rootvg)
  7. rewind, eject and erase  the tape

1. Backup

Using backup and tar command to we can take full backup and incremental backup

Using tar command we can normal backup, in this tar we cannot take day wise incremental backup

#tar –cvf destination source

#tar –cvf /dev/rmt0 /usr/sbin

#backup –if /dev/rmt0 /usr/sbin (For AIX full backup)

/usr/sbin directory files is backup to tape


Using backup command we can take incremental backup, this backup command is particularly for AIX.

In this backup command we can specify the day (0(sun) – 6(sat)).

Suppose you want to take Sunday backup then your command will be

#backup -0 –vf destination source

#backup -0 –vf /dev/rmt0 /var

#backup -6 –vf /dev/rmt0 /var (Saturday backup)

/var file system log is backup to tape

Like this we can take normal and incremental backup in AIX


2. Restore

Using tar and restore command we can restore the data in server

Using tar command we can restore data to server, this is normal restore

#tar –xvf /dev/rmt0

The tape backup is restored to /data directory.

Using restore command we can restore the data

#restore –xdf /dev/rmt0

The tape data is restored in current directory.

Like this we can restore the data in AIX


3. rootvg backup

Using mksysb command we can take the rootvg (AIX OS) backup

#mksysb –i /dev/rmt0

#mksysb –ie /dev/rmt0 (exclude backup – please read NOTE message)

i option is used for crate the image.data file created in tape

This image.data file contains all the file system information’s in rootvg while restore the rootvg backup, before start the restore it will read the information’s from the image.data file

After the command execution rootvg backup created in tap, suppose OS got corrupted, that time we can restore the os from rootvg backup.

NOTE: While taking rootvg backup we can exclude unwanted file systems in backup process. Suppose you not required following file systems in mksysb backup,
/var – log files
That time you should put entry in /etc/exclude.rootvg,


While creating the rootvg backup, first tape is spitted in to 4 blocks (block size is 512)

First block has boot image.

The BOS boot image contains a copy of the system’s kernel and device drivers
needed to boot from the mksysb tape. It is created by the bosboot command.

Second block has following things, 1. /tapeblksize, 2. /image.data, 3. bosinst.data.

1. /tapeblksize

The /tapeblksize file contains the block size the tape drive was set to when the mksysb command was run.

2. /image.data

The /image.data file store the information about rootvg, like vg, pp, pp size, lv, lv size, FS

The image.data file resides in /var/adm/ras/image.data

3. /bosinst.data

The ./bosinst.data file allows you to specify the requirements at the target system
and how the user interacts with the target system. This file contains the
customized BOS install procedures and dictates how the BOS install program will
behave. You can customize this file before issuing the mksysb command or use a
procedure to customize this file after the image backup is done.


Third block has dummy toc file,

The dummy table of contents (TOC) is used so that the mksysb tape contains the
same number of images as a BOS install tape.

Fourth block has data, that is rootvg original data



4. Restore rootvg backup

Using restore command we can restore the rootvg backup

Boot server with bos (base operating system) Cd, then go to maintenance mode and access the rootvg, then run the following command

#restore –T –d –v –q –f /dev/rmt0
Or
Boot server with bos CD, then go to maintenance mode and initiate the rootvg backup (one option available in maintenance mode).

Like this we can restore the rootvg backup


5. Backup the non rootvg backup

Using savevg command we can backup the non rootvg backup

Suppose your server has 3 volume groups

#lsvg
Rootvg
Datavg
Oraclevg
#

Now you want to take datavg backup, then your command will be

#savevg –if /dev/rmt0 /datavg
#savevg –ief /dev/rmt0 /datavg

Datavg volume group is backup to tape

NOTE: While taking restvg backup we can exclude unwanted file systems in backup process. Suppose you not required following file systems in mksysb backup,
/var – log files
That time you should put entry in /etc/exclude.datavg,


6. Restore the non rootvg backup

Using restvg command we can restore the non rootvg backup

#restvg –xdf /dev/rmt0

After command execution datavg backup restored to server with same name while importing vg we can change the vg name.


7. Rewind, Eject, Erase the tape

Using tctl command we can rewind, eject and erase the tape drive.

#tctl –f /dev/rmt0 rewind (To rewind the tape)

#tctl –f /dev/rmt0 eject (To eject the tape)

#tctl –f /dev/rmt0 erase (To erase the tape content)