diff --git a/doc/guix.texi b/doc/guix.texi
index de958c9cf1..056bf011f6 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -2279,6 +2279,12 @@ types.}.  For the ESP, if you have one and assuming it is
 mkfs.fat -F32 /dev/sda1
 @end example
 
+For the root file system, ext4 is the most widely used format.  Other
+file systems, such as Btrfs, support compression, which is reported to
+nicely complement file deduplication that the daemon performs
+independently of the file system (@pxref{Invoking guix-daemon,
+deduplication}).
+
 Preferably, assign file systems a label so that you can easily and
 reliably refer to them in @code{file-system} declarations (@pxref{File
 Systems}).  This is typically done using the @code{-L} option of