A few corrections and clarifications to r343406.

- Use "in" instead of "on" when referring to directory and UFS partition.
- Switch from hw.physmem to hw.realmem and add a description to
distinguish the two.
- Explain why the "df" command is having trouble displaying ZFS sizes
correctly. Add a bit more descriptive text to help why the output of
"zfs list -o space" should be used.
- Switch to vmstat instead of iostat display for systat(1) as it shows
more information on one screen. Describe what is displayed based on the
text of the man page. Change the list of the other values accordingly.
- Sort the flags to "zfs destroy" alphabetically.

Reviewed by:	rgrimes
Approved by:	rgrimes
MFC after:	8 days
Differential Revision:	https://reviews.freebsd.org/D18993

1 files changed, 17 insertions, 10 deletions

diff --git a/usr.bin/fortune/datfiles/freebsd-tips b/usr.bin/fortune/datfiles/freebsd-tips
index 1ec51666002b9..98344090a3bd3 100644
--- a/usr.bin/fortune/datfiles/freebsd-tips
+++ b/usr.bin/fortune/datfiles/freebsd-tips
@@ -275,7 +275,7 @@ To see how much disk space is left on your UFS partitions, use
 	df -h
 		-- Dru <genesis@istar.ca>
 %
-To see the 10 largest files on a directory or UFS partition, use
+To see the 10 largest files in a directory or on a UFS partition, use
 
 	du -h /partition_or_directory_name | sort -rh | head
 		-- Dru <genesis@istar.ca>
@@ -560,10 +560,13 @@ curl -v -d "nickname=$USER" -d "description=FreeBSD/$(uname -m) on \
 $(kenv smbios.system.maker) $(kenv smbios.system.product)" -d "do=addd" \
 --data-urlencode 'dmesg@/var/run/dmesg.boot' http://dmesgd.nycbug.org/index.cgi
 %
-Want to know how much memory (in bytes) your machine has available? Let
+Want to know how much memory (in bytes) your machine has installed? Let
 sysctl(8) tell you with the following command:
 
-sysctl hw.physmem
+sysctl hw.realmem
+
+The realmem value is memory before the kernel and modules are loaded, whereas
+hw.physmem is what is left after they were loaded. 
 
 The number of active CPUs is displayed using this command:
 
@@ -571,20 +574,24 @@ sysctl hw.ncpu
 
 		-- Benedict Reuschling <bcr@FreeBSD.org>
 %
-When using ZFS as the file system the "df" command will display confusing 
-values. Use the built-in "zfs list" command to get an overview of space usage:
+When using ZFS as the file system the "df" command is reporting the pool size
+and not file system sizes. It also does not know about descendent ZFS
+datasets, snapshots, quotas, and reservations with their individual space usage. 
+Use the built-in "zfs list" command to get a better overview of space usage:
 
 zfs list -o space
 
 		-- Benedict Reuschling <bcr@FreeBSD.org>
 %
 To learn more about what your system is doing, take a look at systat(1). For
-example, to get an overview of I/O happening in the system, run:
+example, to get various of statistics related to virtual memory usage, process
+scheduling, device interrupts, system name translation caching, and disk I/O,
+enter the following:
 
-systat -iostat
+systat -vmstat
 
-Other values are icmp, icmp6, ifstat, ip, ip6, netstat, pigs, sctp, swap, tcp,
-vmstat, or zarc. You can switch between displays using :<display> and exit
+Other values are icmp, icmp6, ifstat, iostat, ip, ip6, netstat, pigs, sctp,
+swap, tcp, or zarc. You can switch between displays using :<display> and exit
 back to your shell by typing
 
 :quit
@@ -694,7 +701,7 @@ dataset/snapshot and not any dependent ones. ZFS will display the resulting
 action when -n is combined with the -v option without actually performing
 it:
 
-zfs destroy -rvn mypool@mysnap
+zfs destroy -nrv mypool@mysnap
 
 Once you are sure this is exactly what you intend to do, remove the -n
 parameter to execute the destroy operation.