208 lines
8.9 KiB
Plaintext
208 lines
8.9 KiB
Plaintext
Introduction to Backing Up and Restoring Data
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Jennifer Vesperman
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jenn@linuxchix.org
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2002-02-24
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Revision History
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Revision 0.1 2002-02-16 Revised by: MEG
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Converted from text file. Modified wording.
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Revision 0.2 2002-02-19 Revised by: MEG
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Incorporated Jenn's changes.
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Revision 0.3 2002-02-24 Revised by: MEG
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Conforming to LDP standards.
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This article provides an overview for backing up and restoring data,
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independent of operating system or system architecture. In this article, the
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author explores backup techniques as well as planning backups.
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-----------------------------------------------------------------------------
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Table of Contents
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1. Introduction
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1.1. Copyright Information
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1.2. Overview
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2. Backup Media
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3. Backup Strategies
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4. Restoring
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5. Related links
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1. Introduction
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1.1. Copyright Information
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Copyright (c) 2002 by Jennifer Vesperman. This material may be distributed
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only subject to the terms and conditions set forth in the Open Publication
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License, v0.4 or later (the latest version is presently available at [http://
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www.opencontent.org/openpub/] http://www.opencontent.org/openpub/).
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-----------------------------------------------------------------------------
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1.2. Overview
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All the information you keep in your computer is stored on a hard drive. The
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important thing to know about hard drives is that they have moving parts -
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and like all things which move, those parts wear out eventually. So you need
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to keep a copy of your information on something else as well.
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That's not the only reason to keep a copy somewhere else - your computer may
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be in a fire or a flood. A thief might steal the computer. Lightning might
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strike it. Someone might make a mistake and wipe out your database, without
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doing any damage to the computer itself.
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So we store the data somewhere else as well. Not instead - most things you
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can back your information onto aren't any safer than the hard drive. But
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having it in two places is safer than one. Having it in three is even safer.
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And then we store the backup (the second place) somewhere safe. Preferably in
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a different building - if it's in the same building and the building burns
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down or floods, you've lost both your original information and your copy.
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-----------------------------------------------------------------------------
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2. Backup Media
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There's a bewildering variety of things you can back up onto. There are
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floppy disks, tapes, removable hard disks, rewritable CD-ROMs - and by the
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time you read this, probably three or four other options. Here's the
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important thing: it doesn't matter which type you use.
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It's a good idea to have something which you find easy to use. It's a good
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idea to have something big enough to put a single copy of all your
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information on one physical thing - one tape, or one CD-ROM. Two at most. But
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other than that, it doesn't matter which type you use. There's probably
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someone who understands computers who you trust, even if it's the staff in a
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particular specialist computer store. Take their advice.
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Your backup media (the thing you back up on to) probably comes with software
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which will ask which files you want to back up, and will copy them onto the
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backup media for you. If not, ask your friendly specialist for help - there
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are too many ways to actually do a backup for me to write them all, and
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they'll change by the time you read it anyway. But in the following section,
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I'll give you some advice about what you might want to copy.
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-----------------------------------------------------------------------------
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3. Backup Strategies
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With as much data as is stored on a modern computer system, how do you decide
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what to backup? Should you just put the entire system on a CD or tape and be
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done with it? There are several problems with putting your entire system in a
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backup, not the least of which is cost of tapes and CDs. Also, the time to
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perform a backup is increased when the entire system is stored.
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As long as you have the original CDs for your software, there is no need to
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include the programs themselves in backups. For example, your operating
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system and word processor shouldn't be backed up. The data files, however,
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cannot be recreated so you should include them in backups.
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You DO want to backup:
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<EFBFBD><EFBFBD>*<2A>all your web pages, databases, and anything that you made or would have
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trouble replacing
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<EFBFBD><EFBFBD>*<2A>all the information from your financial software
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<EFBFBD><EFBFBD>*<2A>all the information from inventory control, customer databases, or other
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specialist business software
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<EFBFBD><EFBFBD>*<2A>important correspondence
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<EFBFBD><EFBFBD>*<2A>internal documents (important memos and the like)
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<EFBFBD><EFBFBD>*<2A>anything you would suffer for lack of if it lost
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You MIGHT want to backup:
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<EFBFBD><EFBFBD>*<2A>your email, especially if it has customer queries, contact data, or other
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business-critical information
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<EFBFBD><EFBFBD>*<2A>preferences or bookmarks from web browsers
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<EFBFBD><EFBFBD>*<2A>your personal settings for how your computer works
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<EFBFBD><EFBFBD>*<2A>anything that would be a nuisance if it was lost
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You probably DON'T need to backup:
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<EFBFBD><EFBFBD>*<2A>your operating system, so long as you have the original disks
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<EFBFBD><EFBFBD>*<2A>your software, so long as you have the original disks
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<EFBFBD><EFBFBD>*<2A>strictly temporary files (like a webcache, or anything in the trash can)
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<EFBFBD><EFBFBD>*<2A>anything that you are CERTAIN you won't need if the entire computer
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becomes rubbish.
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How many days worth of information could you afford to lose if your computer
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crashed? What about if your office or home burned down? What about if most of
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your city was wiped out by a tornado or a flood?
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The answers to these questions will tell you how often you should do a
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backup, and roughly where you should store them.
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The computer crash one is for your most frequent backup - usually a daily
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backup, stored in your office or home.
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The office-burned-down is for your next most frequent backup, usually a
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weekly backup stored in a secure place in another building - possibly a
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friend's place, or a friendly business whose backups you store. (Exchange
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backups each week.)
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The final is often a monthly or six-monthly backup, and is stored somewhere
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distant - and in some cases, isn't done at all. It's a matter of choice, and
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what risks you want to take.
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Any backup plan is simply a way of controlling risk. You risk losing a day's,
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a week's, a month's or a year's data - instead of risking losing it all. When
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devising your backup plan, think about how much risk you are willing to take.
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-----------------------------------------------------------------------------
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4. Restoring
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Always make sure you have a way to restore the information from your backup
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to the main system, that doesn't involve using the backup itself. If your
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restoration program is saved as part of your backup copy, you might not be
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able to restore your data in a crisis - because to do the restoration, you
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need the software that has to be restored! It becomes a 'catch-22' situation.
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Usually, having the installation disks for your backup program will prevent
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the 'catch-22'.
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Note Always test the restoration process of your backup. If you have a spare
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computer, test restoring on that. Otherwise, test it on a separate
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folder on your main computer - make sure it doesn't overwrite your
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primary copy of your information!
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In a perfect world, you test your restoration process by getting a blank
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computer, as if you'd lost your computer entirely and were starting from
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scratch. Install the operating system, your main programs, and your backup
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program from their original disks. (make sure those disks are still for sale!
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If your office or home burns down, your insurance company will be buying them
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for you - assuming you're insured.) Then restore your information from the
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backups, using the instructions given in the backup-program's manuals.
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In the real world, do as much of that as you can. At minimum, restore the
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information from your backup tapes (or whatever) into an empty directory of
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your computer's hard drive. DO NOT overwrite your current information!
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Be aware that you will probably need to use exactly the same backup program
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to restore your data as you used to save it. If that program becomes
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unavailable, you will need to check with your local computer-knowledgeable
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person whether you need to change programs, or to keep a copy at each of your
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backup-storage locations. If you do the second, make sure you won't need the
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backup-program just to install the backup program!
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-----------------------------------------------------------------------------
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5. Related links
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<EFBFBD><EFBFBD>*<2A>[http://pcsupport.about.com/?once=true&] Backup and Recovery at About.com
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<EFBFBD><EFBFBD>*<2A>[http://www.linuxdoc.org/LDP/lame/LAME/linux-admin-made-easy/
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backup-and-restore.html] Linux Administration Made Easy, Backup & Restore
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Procedures
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