Loading ...Perform backups for the Linux operating system
This question asked again and again by a new Linux sys admins:
How do I perform backups for my Linux operating system?
So I am putting up all necessary information you ever need to know about backup. The main aim is to provide you necessary software, links and commands to get started as soon as possible.
Backup is essential
First a backup is essential. You need a good backup strategy to:
- Minimize time from disaster such as server failure or human error (file deleted) or acts of God
- To avoid downtime
- Save money and time
- And ultimately to save your job
A backup must provide
- Restoration of a single/individual files
- Restoration of file systems
What to backup?
- User files and dynamic data [databases] (stored in /home or specially configured partitions or /var etc).
- Application software (stored in /usr)
- OS files
- Application configuration files (stored in /etc, /usr/local/etc or /home/user/.dotfiles)
Different types of backups
- Full backups: Each file and directory is written to backup media
- Incremental backups (Full + Incremental backup): This backups are used in conjunction with full backup. These backups will be incremental if each original piece of backed up information is stored only once , and then successive backups only contain the information that changed since the previous one. It use file's modification time to determine which file need to backup.
So when you restore incremental backup:
- First restore the last full backup
- Next every subsequent incremental backup you need to restore
Preferred Backup Media
- Tape (old and trusted method)
- Network (ftp, nas, rsync etc)
- Disk (hard disk, optical disk etc)
Test backups
Please note that whichever backup media you choose, you need to test your backup. Perform tests to make sure that data can be read from media.
Backup Recommendation
My years of experience show that if you follow following formulas you are most likely to get back your data in worst scenario:
(a) Rotate backup media
(b) Use multiple backup media for same data such as ftp and tape
(c) Keep old copies of backups offsite
In short create good disaster recovery plan.
General procedure to restore a Linux/UNIX box
There is not golden rule or procedure but I follow these two methods:
Method # 1: Reinstall everything, restore everything, and secure everything
Use this method (bare metal recovery) if your server is cracked or hacked or hard drive is totally out of order:
- Format everything
- Reinstall os
- Configure data partitions (if any)
- Install drivers
- Restore data from backup media
- Configure security
Method # 2: Use of recovery CD/DVD rom
Use this method if your box is not hacked and system cannot boot or MBR damaged or accidental file deletion etc:
- Boot into rescue mode.
- Debug (or troubleshoot) the problem
- Verify that disk partitions stable enough (use fsck) to put backup data
- Install drivers
- Restore data from backup media
- Configure security
Linux (and other UNIX oses) backup tools
Luckily Linux/UNIX provides good set of tools for backup. We have almost covered each and every tool mentioned below. Just follow the link to get more information about each command and its usage:
- Backing to tape using tar to tape, tar over ssh, cpio, and dump command. tar and friends are good for small backups. For large scale backup or backup that demands large CPU and I/O, use other solution (see below).
- Backing to another server using ftp, ftp to NAS, access NAS server using NFS protocol, access NAS from samba/windows, rsync UNIX/Linux server or windows servers
- Backing to recordable media such as CDR or DVD
It is also recommended that you use RAID or LVM (see consistent backup with LVM) or combination of both to increase reliability of data.
A note about MySQL or Oracle database backup
Backing up database server such as MySQL or Oracle needs more planning. Generally you can apply a table write lock and use mysql database dump utility to backup database. You can also use LVM volume to save database data.
A note about large scale backup
As I said earlier tar is good if you need to backup small amount of data that does not demands high CPU or I/O. Following are recommended tools for backup that demands high CPU or I/O rate:
(a) amanda - AMANDA, the Advanced Maryland Automatic Network Disk Archiver, is a backup system (open source software) that allows the administrator to set up a single master backup server to back up multiple hosts over network to tape drives/changers or disks or optical media.
(b) Third party commercial proprietary solutions:
Top three excellent commercial solutions:
- Veritas Netbackup
- IBM Tivoli Storage Manager
- Legato Networker
If you are looking to perform the tasks of protecting large-scale computer systems use above solutions and following two books will give you good idea:
- Implementing Backup and Recovery: The Readiness Guide for the Enterprise
- This gives you an introduction to backup and recovery concepts in the enterprise and covers disaster recovery, and other solutions such as Veritas Netbackup.
- Backup & Recovery (UNIX)
Recommended further readings
- Charles Curley's - Linux Complete Backup and Recovery HOWTO
- Sample backup shell scripts
Backup article at wikipedia
I hope this small how to provide enough information to anyone to kick start your backup operation. Tell me if I am missing something or if you have a better backup solution or strategy, please comment back.
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Tags: application_configuration, application_software, backup_media, backup_strategy, dynamic_data, incremental_backup, incremental_backups, linux_operating_system, modification_time, necessary_software, optical_disk, os_files, restoration, rsync, server_failure, sys_admins, usr ~ Last updated on: July 4, 2007
My name is Wondwossen , I am from Ethiopia , Africa .I am a system admin at a state bank.I really liked what you have preseted here. It has really helped me a lot. Thank for your effort keep it up
Nice one! Thanks! I recommend to use Unix ‘dump’ and ‘restore’ utilities for entire filesystem backup.
Many thanks for remembering us with some of the useful steps to be undertaken before taking backup.
Also i would like to mention about another backup tool - “MondoRescue”. For me it worked fine - easy backup, recovery, etc. Its even available for the 64 bit machines..