Add diagram of RAID0 / striping with four disks.

Submitted by:	Fukang Chen <loader@freebsdmall.com>

share/images/books/handbook/geom/striping.pic

@@ -0,0 +1,54 @@
+.\" $FreeBSD$
+.PS
+
+define  disk_box {
+	offset = 0.3
+	line dashed from $1 + (-offset, -offset) to ($1.x, $2.y) + (-offset, offset)
+	line dashed from last line.end to $2 + (offset, offset)
+	line dashed from last line.end to ($2.x, $1.y) + (offset, -offset)
+	line dashed from last line.end to $1 + (-offset, -offset)
+}
+
+define disk {
+       ellipse wid 1.4 ht 0.2 fill 0.4
+       line down 0.1 from last ellipse.w
+       line down 0.1 from last ellipse.e
+       arc cw rad 3.4 to last ellipse.w + (0, -0.1)
+       for i = 1 to 4 do {
+       ellipse wid 1.4 ht 0.2 fill 0.4 at last ellipse.s - (0, 0.2) fill 0.4
+       line down 0.1 from last ellipse.w
+       line down 0.1 from last ellipse.e
+       arc cw rad 3.4 to last ellipse.w + (0, -0.1)
+       }
+       disk_box(last ellipse.sw, 1st ellipse.ne)
+}
+
+A: box wid 2 "256k would be written in" "four 64k simultaneous writes" "to each of the four disks"
+
+B1: box ht 0.2 wid 0.3 "64k" at A.e + (0.4, 0.5)
+B2: box ht 0.2 wid 0.3 "64k" at A.e + (0.4, 0.2)
+B3: box ht 0.2 wid 0.3 "64k" at A.e + (0.4, -0.1)
+B4: box ht 0.2 wid 0.3 "64k" at A.e + (0.4, -0.4)
+
+move to A.s + (-0.5, -1.9)
+[disk];"disk 1" at last [].s above
+spline from B4.e then right 0.5 then to last [].e + (-0.2, 0.0) ->
+
+move to last [].e + (0.2,0)
+[disk];"disk 2" at last [].s above
+spline from B3.e then right 1.2 then to last [].e + (-0.4, -0.3) ->
+
+move to last [].e + (0.2,0)
+[disk];"disk 3" at last [].s above
+spline from B2.e then right 2.4 then to last [].e + (-0.8, 0.28) ->
+
+move to last [].e + (0.2,0)
+[disk];"disk 4" at last [].s above
+spline from B1.e then right 4 then to last [].e + (-0.5, 0.6) ->
+
+spline from A.e then up 0.2 then to B1.w
+spline from A.e then up 0.1 then to B2.w
+spline from A.e then down 0.1 then to B3.w
+spline from A.e then down 0.2 then to B4.w
+
+.PE