Friday, February 24, 2006

Disaster Recovery Plans - Backup on Linux

What to Backup ?

Directories to backup is dictated by the partitions used in your Server.

Usually it is user data - /root, /etc, /home, /usr/local

Optionally backup log files and pending emails

/var/log, /var/spool/mail

What is the Backup Media ?

Backups should be on a different server or a Storage Device than the server/data you are trying to backup.

NEVER backup your data to the same partition, nor same disk

Different Scenarios of Backup :

Copying From one Harddisk to another on Same Server :

Type - 1

dd if=/dev/hda1 of=/dev/hdb1 bs=1024k

Incase the hda1 Fails, you can remove hda1 and boot with hdb1 as primary.

Type - 2

Copying /home on /dev/hda1 to a /dev/hdb1 ( backup disk )

#mount /dev/hdb1 /mnt/backup

#( tar cf - /home ) | ( cd /mnt/backup ; tar xvfp - )

#umount /mnt/backup

Type - 3

scp Copying /home on /dev/hda1 to a /dev/hdb1 ( backup disk )

#mount /dev/hdb1 /mnt/backup
# scp -par /home /mnt/backup
#
umount /mnt/backup

Type - 4 ( Consumes Good amount of memory )

find | cpio Copying /home on /dev/hda1 to a /dev/hdb1 ( backup disk )

#mount /dev/hdb1 /mnt/backup
#find /home -print | cpio -pm /mnt/backup
#umount /mnt/backup

To View Contents :
cpio -it < file.cpio

To Extract a file :
cpio -id "usr/share/file/doc/*" < file.cpio

Note : In the above examples /mnt/backup is in hda1

Examples of Incremental Backup script if planning to scp to a different server :

For Creating Date Stamps ---- date '+%Y%m%d'.tar.gz

Simplified tar --newer Incremental Backup example
  • LastBackupTime = `cat /Backup_Dir/Last.txt`
  • tar zcvf --newer $LastBackupTime /Backup_Dir/Date.x.tgz $DIRS
  • echo "Date" > /Backup_Dir/Last.txt
Simplified find | tar Incremental Backup example
  • Cnt = `cat /Backup_Dir/Last.txt`
  • find $DIRS -mtime -$Cnt -print | tar zcvf /Backup_Dir/Date.$Cnt.tgz -T -
  • echo "$Cnt +1" > /Backup_Dir/Last.txt
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2 comments:

gary_no_1 said...

try using rsync

have a look at http://www.mikerubel.org/computers/rsync_snapshots/#Rsync

Sriram said...

Thanks Gary - will add that to this post