1. What can be done to make the system cost same for both 80GB and 40GB disks? Can it be done?

2. We have assumed the resource utilizations to be 100% in the above cases. Is it the same in practice? Give reasons for your answer.

Tool to Evaluate I/O Cost & Performance Input Values: CPU MIPS = 2500 MIPS CPU Cost = 20000 S Width of interleaved memory = 16 ns bytes Memory cycle time = 10 MB/sec Maximum number of SCSI buses and controllers = 20 I/O Bus bandwidth = 1000 SCSI Bus transfer rate = 160 MB/sec Maximum number of disks per SCSI string = 15 500 SCSI Controller overhead = 0.3 ms Cost of each SCSI controller = Number of CPU instructions for an I/O operation = 50000 Average I/O size = 32 KB Input Disk specifications: Disk size = small disk 40 GB large disk 80 GB Cost of Disk per GB = small disk 10 $ large disk 10 $ Maximum number of disks per package = small disk 12 large disk 8 Disk Rotation speed = small disk 15000 RPM large disk 15000 RPM Average seek time = small disk 5 ms large disk 5 ms Disk Transfer rate = small disk 40 MB/sec large disk 40 MB/sec Desired total disk capacity = 1920 GB Cost of enclosure = 1500 S Constraints on Resource Utilization: Limit on disk time utilization = 80 % Limit on utilization of SCSI buses = 40 % Limit on utilization of I/O bus = 75 % Reset Values Specs. of Organization Maximum IOPS Cost of Organization Resource Utilization Help Quit Tool to Evaluate I/O Cost & Performance Input Values: CPU MIPS = 2500 MIPS CPU Cost = 20000 S Width of interleaved memory = 16 ns bytes Memory cycle time = 10 MB/sec Maximum number of SCSI buses and controllers = 20 I/O Bus bandwidth = 1000 SCSI Bus transfer rate = 160 MB/sec Maximum number of disks per SCSI string = 15 500 SCSI Controller overhead = 0.3 ms Cost of each SCSI controller = Number of CPU instructions for an I/O operation = 50000 Average I/O size = 32 KB Input Disk specifications: Disk size = small disk 40 GB large disk 80 GB Cost of Disk per GB = small disk 10 $ large disk 10 $ Maximum number of disks per package = small disk 12 large disk 8 Disk Rotation speed = small disk 15000 RPM large disk 15000 RPM Average seek time = small disk 5 ms large disk 5 ms Disk Transfer rate = small disk 40 MB/sec large disk 40 MB/sec Desired total disk capacity = 1920 GB Cost of enclosure = 1500 S Constraints on Resource Utilization: Limit on disk time utilization = 80 % Limit on utilization of SCSI buses = 40 % Limit on utilization of I/O bus = 75 % Reset Values Specs. of Organization Maximum IOPS Cost of Organization Resource Utilization Help Quit