more changes to disk stuff. no drives run at 160MB, but the bus does

LDP/guide/docbook/Tuning-Linux/disk.sgml

@@ -6,7 +6,7 @@
       Your drive system is one of the places where bottlenecks can
       occur.  All of your database information, boot code, swap
       space, and user programs live on the hard drives.  Hard drives
-      are speeding up, now topping 15,000 RPM and rates
+      are speeding up, now topping 15,000 RPM and bus rates
       of over 160MB per second.  Even at these speeds, drives are still
       much slower than RAM or your CPU, with requests to drives waiting
       for the drive to spin to the right location, read and/or write
@@ -70,8 +70,8 @@
         bound waiting for the drive.  Other devices on the SCSI bus
         can communicate during this time.  Another advantage to SCSI
         is that you can have multiple SCSI controllers on the
-        same bus.  This leads into failover, which we will cover later
-        in this chapter.
+        same bus.  This allows two or more machines to access a single
+	SCSI bus and drives that are on that bus.
       </para>
       <para>
         The increased performance of SCSI and low quantity of
@@ -102,6 +102,7 @@
         very low cost for most single user systems while retaining
         some of the higher performance of SCSI.  But many of the
         features of SCSI are not available in IDE:  external boxes,
+	hot swapping,
         and devices like scanners.  In addition, when an IDE drive
         is asked to do something, that IDE bus is locked while
         the drive processes the request.  IDE devices are usually limited