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diff --git a/sag-0.6.1-www/sag-0.6.1.html/c2187.html b/sag-0.6.1-www/sag-0.6.1.html/c2187.html new file mode 100644 index 0000000..c8d5512 --- /dev/null +++ b/sag-0.6.1-www/sag-0.6.1.html/c2187.html @@ -0,0 +1,318 @@ +<!DOCTYPE HTML PUBLIC "-//Norman Walsh//DTD DocBook HTML 1.0//EN"> +<HTML +><HEAD +><TITLE +>Backups</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet"><LINK +REL="HOME" +TITLE="The Linux System Administrators' Guide" +HREF="book1.html"><LINK +REL="PREVIOUS" +TITLE="Disabling a user temporarily" +HREF="x2166.html"><LINK +REL="NEXT" +TITLE="Selecting the backup medium" +HREF="x2206.html"></HEAD +><BODY +BGCOLOR="#FFFFFF" +TEXT="#000000" +><DIV +CLASS="NAVHEADER" +><TABLE +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TH +COLSPAN="3" +ALIGN="center" +>The Linux System Administrators' Guide</TH +></TR +><TR +><TD +WIDTH="10%" +ALIGN="left" +VALIGN="bottom" +><A +HREF="x2166.html" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +></TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +><A +HREF="x2206.html" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><DIV +CLASS="CHAPTER" +><H1 +><A +NAME="BACKUPS" +>Chapter 10. Backups</A +></H1 +><DIV +CLASS="TOC" +><DL +><DT +><B +>Table of Contents</B +></DT +><DT +><A +HREF="c2187.html#AEN2193" +>On the importance of being backed up</A +></DT +><DT +><A +HREF="x2206.html" +>Selecting the backup medium</A +></DT +><DT +><A +HREF="x2216.html" +>Selecting the backup tool</A +></DT +><DT +><A +HREF="x2240.html" +>Simple backups</A +></DT +><DT +><A +HREF="x2315.html" +>Multilevel backups</A +></DT +><DT +><A +HREF="x2405.html" +>What to back up</A +></DT +><DT +><A +HREF="x2417.html" +>Compressed backups</A +></DT +></DL +></DIV +><BLOCKQUOTE +><P +><P +CLASS="LITERALLAYOUT" +>Hardware is indeterministically reliable. <br> +Software is deterministically unreliable.<br> +People are indeterministically unreliable.<br> +Nature is deterministically reliable.</P +></P +></BLOCKQUOTE +><P +> This chapter explains about why, how, and when to make + backups, and how to restore things from backups.</P +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN2193" +>On the importance of being backed up</A +></H1 +><P +> Your data is valuable. It will cost you time and effort + re-create it, and that costs money or at least personal grief + and tears; sometimes it can't even be re-created, e.g., if it + is the results of some experiments. Since it is an investment, + you should protect it and take steps to avoid losing it. </P +><P +> There are basically four reasons why you might lose data: + hardware failures, software bugs, human action, or natural + disasters. + + <A +NAME="AEN2197" +HREF="#FTN.AEN2197" +>[1]</A +> + + Although modern hardware tends to be quite reliable, it can + still break seemingly spontaneously. The most critical piece + of hardware for storing data is the hard disk, which relies on + tiny magnetic fields remaining intact in a world filled with + electromagnetic noise. Modern software doesn't even tend to + be reliable; a rock solid program is an exception, not a rule. + Humans are quite unreliable, they will either make a mistake, or + they will be malicious and destroy data on purpose. Nature might + not be evil, but it can wreak havoc even when being good. All in + all, it is a small miracle that anything works at all. </P +><P +> Backups are a way to protect the investment in data. + By having several copies of the data, it does not matter as much + if one is destroyed (the cost is only that of the restoration + of the lost data from the backup). </P +><P +> It is important to do backups properly. Like everything + else that is related to the physical world, backups will fail + sooner or later. Part of doing backups well is to make sure + they work; you don't want to notice that your backups didn't work. + + <A +NAME="AEN2201" +HREF="#FTN.AEN2201" +>[2]</A +> + + Adding insult to injury, you might have a bad crash just as + you're making the backup; if you have only one backup medium, + it might destroyed as well, leaving you with the smoking ashes + of hard work. + + <A +NAME="AEN2203" +HREF="#FTN.AEN2203" +>[3]</A +> + + Or you might notice, when trying to restore, that you forgot to + back up something important, like the user database on a 15000 + user site. Best of all, all your backups might be working + perfectly, but the last known tape drive reading the kind of + tapes you used was the one that now has a bucketful of water + in it. </P +><P +> When it comes to backups, paranoia is in the job + description. </P +></DIV +></DIV +><H3 +>Notes</H3 +><TABLE +BORDER="0" +CLASS="FOOTNOTES" +WIDTH="100%" +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="5%" +><A +NAME="FTN.AEN2197" +HREF="c2187.html#AEN2197" +>[1]</A +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="95%" +><P +>The fifth reason is ``something + else''.</P +></TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="5%" +><A +NAME="FTN.AEN2201" +HREF="c2187.html#AEN2201" +>[2]</A +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="95%" +><P +>Don't laugh. This has happened to + several people.</P +></TD +></TR +><TR +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="5%" +><A +NAME="FTN.AEN2203" +HREF="c2187.html#AEN2203" +>[3]</A +></TD +><TD +ALIGN="LEFT" +VALIGN="TOP" +WIDTH="95%" +><P +>Been there, done that...</P +></TD +></TR +></TABLE +><DIV +CLASS="NAVFOOTER" +><HR +ALIGN="LEFT" +WIDTH="100%"><TABLE +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +><A +HREF="x2166.html" +>Prev</A +></TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="book1.html" +>Home</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +><A +HREF="x2206.html" +>Next</A +></TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +>Disabling a user temporarily</TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +> </TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +>Selecting the backup medium</TD +></TR +></TABLE +></DIV +></BODY +></HTML +>
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