
                                      without           with
                                  Seek-Optimizing  Seek-Optimizing  Improvement
                                    Disk Driver      Disk Driver
-------------------------------------------------------------------------------
A) Cylinders passed per Disk-Seek:  
Average from all log.Volumes	    3o5.0 Cyls       162.0 Cyls        47 % 
Volume A ( Cyls:   0 ... 196 )      436.5  "	     170.5  "          61 "
Volume C ( Cyls: 196 ... 393 )      292.5  "         163.o  "          44 "
Volume D ( Cyls: 393 ... 589 )      232.5  "         171.0  "          26 "
Volume E ( Cyls: 589 ... 786 )      264.5  "         146.0  "          45 "
Volume F ( Cyls: 786 ... 982 )      356.5  "         118.0  "          67 "
Improvement measured between
Driver and Drive Interface
Average from all log.Volumes	     40.0  %  
Volume A ( Cyls:   0 ... 196 )       42.0  "
Volume C ( Cyls: 196 ... 393 )       37.0  "      
Volume D ( Cyls: 393 ... 589 )       24.0  "         
Volume E ( Cyls: 589 ... 786 )       38.0  "         
Volume F ( Cyls: 786 ... 982 )       59.5  "
B) Percentage of Disk-Accesses with
   Head-Movement per log.Volume:
Volume A ( Cyls:   0 ... 196 )       98.0  %	      95.5  %          
Volume C ( Cyls: 196 ... 393 )       97.5  "          94.5  "          
Volume D ( Cyls: 393 ... 589 )       98.0  "          96.5  "          
Volume E ( Cyls: 589 ... 786 )       98.5  "          96.0  "          
Volume F ( Cyls: 786 ... 982 )       99.0  "          95.5  "          
C) Percentage of Disk-Directory-Ac-
   cesses per log. Volume:
Volume A (Allocatn.Blocksize: 2K)    36.5  %	      70.0  %          
Volume C ( "   "     "   "  : 2K)    45.5  "          46.0  "          
Volume D ( "   "     "   "  : 4K)    34.0  "          34.0  "          
Volume E ( "   "     "   "  : 8K)    29.0  "          26.0  "          
Volume F ( "   "     "   "  :16K)    23.0  "          20.0  "          




   Fig. 16.2: Order Entry Simulation with 9 Users on 5 log. Volumes
              Influence of Seek-Optimizing Disk Driver
              Slave 1 operates on Volume D
