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Calculating the number of cylinders on page 3-17
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Calculating the number of bitmap areas on page 3-17
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Calculating the number of available bitmap areas on page 3-18
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Calculating the maximum number of pairs on page 3-18
Calculating the number of cylinders
To calculate the number of cylinders, start by calculating the number of
logical blocks, which indicates volume capacity measured in blocks.
number-of-logical-blocks = volume-capacity (in bytes) / 512
Then use the following formula to calculate the number of cylinders:
number-of-cylinders = ceiling(ceiling(number-of-logical-blocks /
512) / 15)
Related topics
•
Maximum number of GAD pairs on page 3-16
•
Calculating the number of bitmap areas on page 3-17
Calculating the number of bitmap areas
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.
Related topics
•
Maximum number of GAD pairs on page 3-16
Planning for global-active device
3-17
Hitachi Virtual Storage Platform G1000 Global-Active Device User Guide
Summary of Contents for G1000
Page 8: ...Index viii Hitachi Virtual Storage Platform G1000 Global Active Device User Guide ...
Page 14: ...xiv Preface Hitachi Virtual Storage Platform G1000 Global Active Device User Guide ...
Page 238: ...9 18 Troubleshooting Hitachi Virtual Storage Platform G1000 Global Active Device User Guide ...
Page 245: ...Hitachi Virtual Storage Platform G1000 Global Active Device User Guide ...