DB2 Help

Specifications for Drive -- Fields and controls

Questions for recommended specifications

Questions for recommended specifications

Answer these questions to get recommended average seek time, rotation speed, and transfer rate in the Recommended specifications group. The recommended specifications are used to calculate settings for overhead and transfer.

How big is the physical drive?

Less than 500 MB
Recommends slower specifications
Between 500 MB and 1 GB
Recommends mid range specifications
More than 1 GB
Recommends faster specifications

Specify the size of the physical drive, not a logical partition of the drive.
The recommended specifications are based on the fact that hard drives of similar sizes have similar specifications.
How old is the physical drive?
Select 1995 or newer if the drive was new in or after 1995. If you are not sure, guess based on the age of the computer.
Selecting 1995 or newer recommends faster specifications.

The recommendation is based on the fact that newer drives of a given size tend to have faster specifications.
The physical drive is in a
Select High performance server if the drive is in a computer designed to act as a data server.
Selecting High performance server recommends faster specifications.
The recommendation is based on the fact that servers tend to have drives with faster specifications.

Recommended specifications

These fields contain the recommended average seek time, rotation speed, and transfer rate based on the answers you specify in the Questions for recommended specifications. However, if you can get the exact specifications from the drive manufacturer, you can modify the fields directly.

Average seek time: The value in this field is used to calculate the overhead setting.
Rotation speed: The value in this field is used to calculate the overhead setting.
Transfer rate: The value in this field is used to calculate the transfer setting.

Calculated settings

The overhead and transfer values in these fields are calculated from the values in the Average seek time, Rotation speed, and Transfer rate fields in the Recommended specifications which in turn are recommended based on the answers you specify in the Questions for recommended specifications.

However, you calculated the settings manually, you can modify the fields directly.

Overhead

This value is calculated using the following formula:

overhead = avg seek time + ( ( ( 1 / rotation speed ) * 60 * 1000 ) / 2 )

Transfer

This value is calculated using the following formula:

transfer = ( 1 / transfer rate ) * 1000 / 1024000 * 4096