Calculating the number of bitmap areas

Global Active Device for VSP One Block

Version
10.5.x
File Size
25537 KB
Audience
anonymous
Part Number
MK-23VSP1B011-11
ft:lastEdition
2026-06-23

Calculate the number of bitmap areas using the number of cylinders.

number-of-bitmap-areas = ceiling((number-of-cylinders × 15) / 122,752)

122,752 is the differential quantity per bitmap area. The unit is bits.

Note: You must calculate the number of required bitmap areas for each volume. If you calculate the total number of cylinders in multiple volumes and then use this number to calculate the number of required bitmap areas, the calculation results might be incorrect.

The following are examples of correct and incorrect calculations, assuming that one volume has 10,017 cylinders and another volume has 32,760 cylinders.

  • Correct:

    ceiling((10,017 × 15) / 122,752) = 2

    ceiling((32,760 × 15) / 122,752) = 5

    The calculation result is seven bitmap areas in total.

  • Incorrect:

    10,017 + 32,760 = 42,777 cylinders

    ceiling((42,777 × 15) / 122,752) = 6

    The calculation result is six bitmap areas in total.