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diff --git a/doc/walkthrough.mdwn b/doc/walkthrough.mdwn
index 281f46050..9d4d2ce59 100644
--- a/doc/walkthrough.mdwn
+++ b/doc/walkthrough.mdwn
@@ -339,3 +339,31 @@ might say about a badly messed up annex:
 	git-annex: Only 1 of 2 copies exist. Run git annex get somewhere else to back it up.
 	failed
 	git-annex: 2 failed
+
+## backups
+
+git-annex can be configured to require more than one copy of a file exists,
+as a simple backup for your data. This is controled by the "numcopies"
+setting, which defaults to 1 copy. Let's change that to require 2 copies,
+and send a copy of every file to a USB drive.
+
+	# echo "* git-annex-numcopies=2" >> .gitattributes
+	# git annex copy . --to usbdrive
+
+Now when we try to `git annex drop` a file, it will verify that it
+knows of 2 other repositories that have a copy before removing its
+content from the current repository.
+
+You can also vary the number of copies needed, depending on the file name.
+So, if you want 3 copies of all your flac files, but only 1 copy of oggs:
+
+	# echo "*.ogg git-annex-numcopies=1" >> .gitattributes
+	# echo "*.flac git-annex-numcopies=3" >> .gitattributes
+
+Or, you might want to make a directory for important stuff, and configure
+it so anything put in there is backed up more thoroughly:
+
+	# mkdir important_stuff
+	# echo "* git-annex-numcopies=3" > important_stuff/.gitattributes
+
+For more details about the numcopies setting, see [[copies]].