daemon: Rename '--disable-store-optimization' to '--disable-deduplication'.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_DISABLE_STORE_OPTIMIZATION):
  Rename to...
  (GUIX_OPT_DISABLE_DEDUPLICATION): ... this.  Adjust user accordingly.
  (options): Add "disable-deduplication".  Make
  "disable-store-optimization" a hidden alias.
* doc/guix.texi (Invoking guix-daemon): Adjust to new option name.  Add
  index entry.  Improve description.

1 files changed, 7 insertions, 5 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index b6cd57acc2..e34a70f0df 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -506,14 +506,16 @@ Unless @code{--lose-logs} is used, all the build logs are kept in the
 @var{localstatedir}.  To save space, the daemon automatically compresses
 them with bzip2 by default.  This option disables that.
 
-@item --disable-store-optimization
+@item --disable-deduplication
+@cindex deduplication
 Disable automatic file ``deduplication'' in the store.
 
 By default, files added to the store are automatically ``deduplicated'':
-if a newly added file is identical as another one found in the store,
-the daemon makes the new file a hard link to the other file.  This
-slightly increases the input/output load at the end of a build process.
-This option disables this.
+if a newly added file is identical to another one found in the store,
+the daemon makes the new file a hard link to the other file.  This can
+noticeably reduce disk usage, at the expense of slightly increasde
+input/output load at the end of a build process.  This option disables
+this optimization.
 
 @item --gc-keep-outputs[=yes|no]
 Tell whether the garbage collector (GC) must keep outputs of live