IBM Tivoli Monitoring > Version 6.3 Fix Pack 2 > Installation Guides > Installation Guide > Performance tuning > Tivoli Data Warehouse > Relational database design and performance tuning for DB2 Database servers > Hardware design and operating system usage > I/O
IBM Tivoli Monitoring, Version 6.3 Fix Pack 2
Selecting disk drives
Disks tend to grow larger every year, doubling in capacity every 18 months, and the cost per GB is lower each year. The cost difference of the two smallest drives diminishes until the smaller drive is not practical. The disk drives improve a little each year in seek time. The disk drives get smaller in physical size. While the disk drives continue to increase capacity with a smaller physical size, the speed improvements, seek, and so on, are small in comparison. A database that would have taken 36 * 1 GB drives a number of years ago can now be placed on one disk.
This growth trend highlights database I/O problems. For example, if each 1 GB disk drive can do 80 I/O operations a second, the system can process a combined 2880 I/O operations per second (36 multiplied by 80). But a single 36-GB drive with a seek time of 7 milliseconds can process only 140 I/O operations per second. Although increasing disk drive capacity is beneficial, fewer disks cannot deliver the same I/O throughput.
Parent topic:
I/O