Bring documentation up to date, add a few more vnconfig examples.

1 files changed, 28 insertions, 0 deletions

diff --git a/usr.sbin/vnconfig/vnconfig.8 b/usr.sbin/vnconfig/vnconfig.8
index 7cfe5170..9b2e3c8 100644
--- a/usr.sbin/vnconfig/vnconfig.8
+++ b/usr.sbin/vnconfig/vnconfig.8
@@ -225,6 +225,34 @@ Unmounts (disables)
 .Pp
 Configures and enables all devices specified in
 .Pa /etc/vntab .
+.Pp
+.Dl vnconfig -s labels -c vn0 somebackingfile
+.Dl disklabel -r -w vn0 auto
+.Dl disklabel -e vn0
+.Pp
+Is an example of how to configure a file-backed VN disk with a disk label 
+and to initialize and then edit the label.  Once you create the label, you
+can partition your VN disk and, for example, create a filesystem on one of
+the partitions.  If you are using a file as backing store, it may be possible
+to recover your VN disk after a crash by vnconfig'ing the same file again
+and using the VN configuration already stored in the file rather then 
+relabeling and recreating the filesystem.  It is even possible to fsck the
+VN partitions that previously contained filesystems.
+.Pp
+.Dl vnconfig -e -s labels,reserve -S 400m vn0
+.Dl disklabel -r -w vn1 auto
+.Dl newfs /dev/rvn1c
+.Dl mount /dev/vn1c /usr/obj
+.Pp
+Is an example of a swap-backed VN disk configuration.  This example assumes
+that you have at least 400 megabytes of swap free (and hopefully much more).
+The swap space is pre-reserved in order to maintain maximum performance.
+We then label the disk, newfs it, and mount it as /usr/obj.  Swap-backed VN
+devices are recoverable after a crash if you (A) use the reserve flag, and if
+(B) the same swap is reserved as was the last time, meaning that such 
+vnconfig's would have to be run in your rc.local.  In general, though, you
+only use swap-backed VN devices to hold information you don't mind losing
+on every reboot.
 .Sh SEE ALSO
 .Xr mount 2 ,
 .Xr swapon 2 ,